October 2001
By John Brumm

Dive Computers Reviewed in This Article

| Aeris 300G Aeris Atmos Pro Genesis Scuba ReAct Genesis Scuba Resource Mares Surveyor Mares Surveyor Nitrox Mares Tutor Oceanic Data 100 Oceanic DataPlus | Oceanic DataPlus2 Oceanic Prodigy Oceanic XTC-100 SCUBAPRO Aladin Pro Ultra SCUBAPRO Aladin Sport Plus Sherwood Scuba Logic Suunto Mosquito Suunto Stinger Suunto Vyper |
Since the introduction of the first successful electronic dive computer, the Orca Edge in 1983, dive computers have been steadily improving, adding more features and functions as they go. The 18 dive computers reviewed here are the best non-integrated (no air or gas function) computers available.

The Testing

In the lab, using a small chamber (pressure pot), we tested all 18 computers simultaneously on nine controlled dive profiles, including:

• Three separate dives to the maximum no-decompression limit at 50, 100 and 150 feet.

• A sawtooth dive from 60 to 100 feet, repeating these ups and downs to the maximum no-decompression limit.

• A reverse-profile dive of 60 feet for 45 minutes followed one hour later by a 130-foot dive to the maximum no-decompression limit.

• Repeated bounce dives to 130 feet for 10 minutes every hour until the computers were violated.

In addition, a check of the dive computer's ability to track depth and time accurately was conducted during several of the dives.

For the dive profiles conducted in the field, we took all 18 computers on 12 actual dives over a six-day period, gathering data on multilevel, repetitive, multiday diving. These dives were typically to 100 feet for 45 minutes followed 45 minutes later by a dive to 60 feet for 50 minutes.

The results of the test profiles listed above are used to develop the Freedom (time under water) vs. Risk (of DCS) Chart. The use of multiple profiles is a necessary procedure. A computer's relative conservatism changes depending on dive profile, but it's best to have an overall idea of a computer's behavior.

Ergonomic ocean testing is focused on a diver's ability to see, read and understand the data displayed, and the ability to switch functions--essentially the user-friendliness of each dive computer. The six test divers each dived all 18 computers, evaluating ergonomic characteristics. All six divers are highly experienced in gear testing; five of them are underwater instructors and one is a divemaster. The testers were Vicki Durst, Jon Hardy, Bruce Haveri, Jason Manix, Ron Moore and Lorraine Sadler.

Aeris 300G & Atmos Pro

| Aeris Atmos Pro| Aeris 300G
Price: $599.95.
Mounting: Console.
User control: Two push buttons.

Aeris Atmos Pro
Price: $399.95.
Mounting Options: Module, wrist, console, BC.
User control: Two push buttons.

Thumbs Up: Large, easy-to-read numbers and oxygen/nitrogen bar graphs; Green/yellow/red highlighting; Easy-to-use dual-button controls; Backlit screen for use both under water and on the surface; Well-designed owner's manual and waterproof on-site prompt card; PC-downloadable; User-replaceable batteries.

Thumbs Down: Universal icons difficult to see at depth; Control buttons not labeled; Switching functions under water takes some getting used to; Time to fly is an arbitrary countdown.

The Atmos Pro is available in module, wrist, console with pressure gauge or console with pressure gauge and compass mountings. The 300G, essentially the same computer as the Atmos Pro, comes in a console with pressure gauge and compass. The console package is ergonomically designed, enabling at-a-glance viewing of all three instruments, and features audible pressure, depth and ascent alarms and a low-pressure warning. Backlighting in both the computer and pressure gauge makes night dives and low-visibility situations easier to manage.

Easy-to-operate "advance" and "select" buttons are key to the ease with which Aeris computers allow the user to select various display options and access specific information on demand. Designed for multilevel diving, these computers are liberal on single dives but become conservative on subsequent deep dives. Both computers are nitrox-programmable. The dive log mode stores your 12 latest dives and allows you to download up to 50 dives to a PC. Power is supplied by two three-volt lithium cells for 50 24-hour periods of activation time; when the low-battery icon flashes, you can find replacements at any Radio Shack and install them yourself.

Genesis Scuba ReAct & Scuba Resource

| Genesis Scuba Resource| Genesis Scuba ReAct
Price: $400.
Mounting Options: Console, wrist, hose, BC.
User control: Two push buttons.

Thumbs Up: "Left" and "right" control buttons; Excellent nitrogen loading graphic display; Crisp numbers for optimum readability; Choice of 15 modes on three screens, all user-selectable; Three-color highlighting; Alternate display for nitrox diving; Desaturation time can be used as time to fly; "HydroGlow" backlighting for both underwater and surface use; PC-downloadable; User-friendly owner's manual; User-replaceable battery.

Thumbs Down: Difficult to read red bar along right edge of screen while at depth (letters used for labels are too small); Time to fly is an arbitrary countdown.

Genesis Scuba Resource
Price: $300.
Mounting Options: Console, wrist, BC.
User control: One push buttons.

Thumbs Up: Budget pricing; Highly readable and understandable screen; Excellent dive profile graphics; User-friendly owner's manual; User-replaceable batteries.

Thumbs Down: Display cycles too quickly; Difficult to read red bar along right edge of screen while at depth (black type blends in with red background); Time to fly is an arbitrary countdown.

Three dive mode screens accessed by two push-button controls result in an impressive collection of diver-selectable displays on the ReAct. By repeatedly pressing the control buttons or holding down to scroll, you're able to set or access a variety of displays while on the surface or under water, using air or nitrox, or even when in decompression. Having so much information available necessitates downsizing letters, numbers and icons to the point where they are sometimes difficult to discern at depth, but a thoughtful screen layout tends to minimize this annoyance.

The ReAct provides nitrox capability without allowing this function to interfere with its primary use as a standard air dive computer. And the 50 percent nitrox default is user-selectable so you can shut it off when necessary. Able to read depths to 330 feet, the ReAct stores your 12 most recent dives in the dive log mode. Additional dive data can be downloaded to your PC using the optional Data Retrieval System (DRS).

Tests indicate that a new Tadiran 1/2 AA model TL-2150 lithium battery will maintain computer operation for approximately 350 dive hours at one one-hour dive per dive day, or 700 dive hours at two or more one-hour dives per dive day. To conserve battery power you can turn off the backlight. The battery is user-replaceable.

A very successful, extremely reliable dive computer, the Resource is the most affordable computer in this group. Known as a solid no-frills dive computer, the Resource accesses your dive information in eight distinct dive modes (including violation) via a single button. The dive mode screen offers bold numbers, extremely intuitive no-decompression limit diamonds and rapid ascent bars.

The Resource reads a maximum depth of 250 feet, offers "HydroGlow" screen illumination in dive mode, provides decompression stops up to 40 feet and will store a dozen of your most recent dives for future reference. Two lithium three-volt cells provide the juice for approximately 50 activation periods of 24 hours each. This means one pair of cells can give you from as few as 50 dives (if only one dive is conducted each activation period) to more than 150 dives (if three dives are conducted). And when you finally run out of juice, you can replace the batteries yourself.

Mares Surveyor, Surveyor Nitrox & Tutor

| Mares Tutor| Mares Surveyor
Price: $479.
Mounting Options: Console, wrist, BC.
User control: Two push buttons and electrical contacts.

Mares Surveyor Nitrox
Price: $514.
Mounting Options: Console, wrist, BC.

User control: Two push buttons and electrical contacts.

Thumbs Up: Dual push-button controls with easy-to-follow prompts; Powered by user-replaceable AAA batteries; Does not lose memory during battery changes; Effective system for safety stops; Excellent backlighting; Variable ascent rate with graph and percentage; Extensive logged memory and history; Two triangles clearly indicate optimum decompression level; Desaturation time can be used as time to fly.

Thumbs Down: Difficult to read red bar along right edge of screen while at depth (letters used for labels are too small); Time to fly is an arbitrary countdown.

Mares Tutor
Price: $379.
Mounting Options: Console, wrist, BC.
User control: Two push buttons and electrical contacts.

Thumbs Up: Budget pricing; Dual push-button controls with easy-to-follow prompts; Powered by user-replaceable AAA batteries; Does not lose memory during battery changes; Good system for safety stops; Excellent backlighting; Variable ascent rate with graph and percentage; Extensive logged memory and history; Two triangles clearly indicate optimum decompression level; Desaturation time can be used as time to fly.

Thumbs Down: Hard to read labels along the edges of the screens; Ghost images apparent on the LCDs; Short battery life; Leans toward the conservative on repeated deep dives; Mediocre owner's manual.

The Surveyor and Surveyor Nitrox continue to support a loyal following with their reputation for diver-friendliness. Powered by a common AAA battery, you can squeeze only about three months or 50 dives, or a mere 20 hours (10 with nitrox) if you consistently use the backlight feature, but you can buy the batteries anywhere. They're inexpensive and user-replaceable.

A dual-button control pad allows you to access a variety of traditional dive functions. You have the option of customizing your computer with a dozen different settings, including the ability to make an already relatively conservative computer even more so by readjusting the altitude setting. You can review the profiles of your past 20 dives and then store up to 50 dives in the logbook memory, which can be downloaded to your PC with the optional PC interface kit. Both computers read diving depths up to 500 feet.

With its additional information, the nitrox version is not as easy to read as the standard Surveyor because a lot of information is crammed into a limited space. But it's info you won't want to do without. For example, max depth is always visible on the display.

Alas, Mares owner's manuals continue to be difficult to interpret. With their microscopic type, lack of descriptive illustrations and sections in six languages, information tends to be unclear, sometimes incomplete, and a hassle to dig out.

The Tutor offers basically the same features as the Surveyor but is not as extensive in some functions. For example, the Tutor will log only 20 dives for PC download, and profiles only 10 dives. Maximum operating depth is 325 feet.

All Mares computers can be started either manually with the push buttons or automatically via water-activated electrical contacts, although as with all dive computers, we recommend you start them on the surface before the dive.

Like the two Surveyor models, the Tutor sports features that some divers might consider excess baggage. Fortunately, none of these features get in the way of computer performance. For example, there is an uncontrolled-ascent function that can cause a violation and a lockout. But if you don't like it, you can turn it off. Also, the Underwater Behavior Analysis (UBA) simulator, unique to Mares computers, will flag a warning if you engage in what Mares considers "unsafe" behavior--but you're not penalized; it's purely for your own information. {mospagebreak}

Oceanic DataPlus, DataPlus2, XTC-100, Prodigy, Data 100

| Oceanic Data 100| Oceanic DataPlus
Price: $379.95.
Mounting Options: Console, hose, wrist, BC.
User control: One push button.

Oceanic DataPlus2
Price: $419.95.
Mounting Options: Console, hose, wrist, BC.
User control: Two push buttons.

Thumbs Up: Easy to read and understand; Incorporates green/yellow/red graphic highlighting; Nitrox-capable; Excellent owner's manual and waterproof prompt card; User-replaceable batteries (DataPlus--two three-volt lithiums, DataPlus2--one 3.6-volt 1/2 AA lithium); Ascent-rate indicator; Easy adjusting of no-decompression limits at any time with use of the nitrogen graph; Reasonably handles multilevel and repetitive diving scenarios; Multiple user settings; PC-downloadable.

Thumbs Down: Information in the red zone difficult to make out at depth; Log tends to scroll too fast on the DataPlus; Time to fly is an arbitrary countdown; Tends toward the conservative on repeated deep dives.

Oceanic XTC-100
Price: $499.95.
Mounting Options: Wrist, BC (with transit clip).
User control: Two push buttons.

Thumbs Up: Big bold numbers and crisp, clear graphics; Three-color highlighting; Easy-to-operate dual control buttons; Three display screens including a large format alternate display; Nitrox-capable; No-decompression limits are easily adjustable with bar graph; Both "Oceanglo" and "Smartglo" backlighting; Both audible alarm and oxygen default (in nitrox mode) can be user-controlled; Handles multilevel and repetitive diving well; User-replaceable battery; Excellent owner's manual with waterproof prompt card.

Thumbs Down: Hard to find dive time; Dive numbers too far apart; Jumps around depth and decompression information; Symbols used as labels are sometimes difficult to recognize; Time to fly is an arbitrary countdown.

Oceanic Prodigy
Price: $305.95.
Mounting Options: Console, hose, wrist, BC (with transit clip).
User control: One push button.

Oceanic Data 100
Price: $430.95.
Mounting Options: Console, hose, wrist, BC.
User control: One push button.

Thumbs Up: Simple to operate; Easy to read and understand; Three-color highlighting; Bold oxygen/nitrogen bar graphs; Excellent dive profile graphics; Superb owner's manuals.

Thumbs Down: Difficult to access alternate screen at depth; Hard to push button with gloves on; No waterproof prompt card; Time to fly is arbitrary.

The DataPlus and its more versatile cousin the DataPlus2 maximize the use of bold graphics and three-color highlighting, which makes the ascent-rate indicator easier to follow and increases control during safety stops--simply stay at 15 feet until you've cleared the yellow zone and the nitrogen loading bar inches back into the green.

Both computers operate at a maximum depth of 330 feet, have a 12-dive profile capacity and "Oceanglo" push-button underwater backlighting and are nitrox-capable.

Rather than presetting these computers for a degree of conservatism, you can use the DataPlus's nitrogen loading display to adjust the degree of conservatism by simply backing off the computer's limits as you dive.

The DataPlus uses a single push button to start, to call up information and to change settings, so it takes some patience cycling through dive modes. The DataPlus2, in contrast, utilizes two control buttons, which provide "on demand" dive data on alternate screen displays. This more powerful model offers you the flexibility to turn off the 50-percent-oxygen nitrox default. In addition to DataPlus features, the DataPlus2 offers "Smartglo" sensor backlighting for surface illumination, a desaturation countdown, more than triple the battery life (350 hours) of the DataPlus, a real time clock and the ability to download over 200 dives to a PC (versus about 40 for the DataPlus).

A useful function of these Oceanic dive computers is the delayed violation status, allowing you to correct an error or get out of a difficult predicament such as going above the deco stop, exceeding maximum depth or having an extremely deep deco stop. Once in permanent violation, these computers work as gauges, providing depth and time but no decompression info for 24 hours. If you continue to dive, the 24-hour period keeps extending until you have gone 24 hours with no dives.

All of Oceanic's owner's manuals are excellent, and these two particular models offer waterproof prompt cards. They are available in compass mount, hose mount or wrist mount configurations.

The XTC-100's big-digit display makes this wrist-mount dive computer a favorite among divers with tired eyes. Extremely user-friendly, the secret lies in the two push-button controls that let you venture through pre-dive settings like alarms and defaults, dive modes for both compressed air and nitrox profiles, and post-dive modes enabling you to access dive history.

Useful features include a 12-dive history mode. To further increase usability, it offers both "Smartglo" backlighting for surface use and "Oceanglo" backlighting when operating at depth. The unit has visible and audible alarms, an oxygen loading graph, a variable ascent rate indicator and enough battery power to run for 100 hours at one one-hour dive per dive day or up to 300 dive hours at three one-hour dives per dive day. Power comes from a 3.6 volt 1/2 AA lithium battery.

Oceanic is known for using icon-type symbols to help you find and identify your dive data. But as computers get more complex, icons are getting smaller and harder to understand. Fortunately, the data that is not numerically displayed is still available on the screen in graph form.

The Prodigy has long been a popular budget-priced dive computer. Information is accessed via eight distinct dive modes (including violation). Bold numbers and no-decompression-limit bars combined with intuitive graphics take the confusion out of monitoring your dive status while at depth.

The Data 100 offers everything the Prodigy does and a little more. For example, the Data 100 has a maximum operating depth of 300 feet, the Prodigy reads to 249 feet. The Data 100 logs 12 dives, the Prodigy 10. Plus, the Data 100 allows you to store and download up to 40 dives to PC, and is outfitted with both Oceanic's "Oceanglo" underwater backlighting system and an extended-depth algorithm.

Both of these models are single-button-control, non-nitrox computers. They feature visible alarm systems, can operate approximately 100 hours on two user-replaceable, three-volt lithium cells, and are available as wrist mounts, hose mounts or compass mounts.

We can't say enough for Oceanic's excellent owner's manuals, which are clear, concise and chock full of big bold illustrations and graphics to make getting to know your computer a pleasurable process.

SCUBAPRO Aladin Pro Ultra & Aladin Sport Plus

| | SCUBAPRO Aladin Sport Plus| SCUBAPRO Aladin Pro Ultra
Price: $500.
Mounting Options: Console, wrist, BC.
User control: Electrical contacts.

SCUBAPRO Aladin Sport Plus
Price: $350.
Mounting Options: Console, wrist, BC.
User control: Electrical contacts.

Thumbs Up: Big numbers; Easy to understand all information continuously; Time to fly actually calculated and displayed; PC-downloadable; Excellent dive profiles; Long-life batteries; Variable ascent rate; Protective screen shield; Backlighting for both surface and under water; Budget pricing for the Sport Plus.

Thumbs Down: Capable of complete lockout--no gauge mode, no access without a PC; Computers are set for fresh water (they read 103 feet when at 100 feet in seawater).

All of Scubapro's Uwatec-made dive computers have a reputation for crisp, easy-to-read displays, although their water-activated controls are not intuitive and require remembering which two contacts to touch to reveal specific dive data. These computers are unique in that they are self-adjusting; they automatically factor in such variables as water temperature, rate of ascent and possible microbubbles to their diving computations. Many divers like this because it eliminates potential human error; others feel this makes the computers too conservative and takes control away from the user.

The Aladin Sport Plus is basically an Aladin Sport with the addition of a flip-up screen guard and an active backlighting system that can be used on the surface and under water. Like the Aladin Sport, the Sport Plus does not include nitrox functions. It does, however, offer a variable ascent rate that enables you to ascend faster while at depth, then slow your ascent as you near the surface. The computer provides a continuous display of your no-decompression time as well as current depth, maximum depth and elapsed dive time. Curiously, the Sport Plus starts its dive planner at 50 feet instead of 30 feet like all other models. And the screen guard, while great for protecting the computer face from chips and scratches, is a potential trap for sediments that can obscure the screen.

The Aladin Pro Ultra enables you to dive on compressed air or on nitrox mixes. It is basically an Aladin Pro Nitrox computer with the addition of the screen cover and backlighting. This unit greatly enhances time spent under water for divers who want to plan and conduct decompression dives.

By using Uwatec's "DataTrak" software and a PC, dive data from both models can be downloaded for future reference. Apart from your last 200 minutes of diving, 37 dives are recorded in the computers' memories. If data are transferred regularly into Uwatec's "MemoMouse," a black box for field use, and then to a PC, all dives can be PC-stored along with their profiles.

Uwatec's owner's manuals are a bit intimidating at first glance. They are literally an inch thick and are printed in six languages. But once you find the right language and wade into the pages, you'll find the information you need.

Both the Aladin Pro Ultra and the Aladin Sport Plus are powered by a special Uwatec battery that's supposed to last between four and 10 years, depending on how many dives (50 to 300) are made each year. Batteries must be replaced at the factory.

Sherwood Scuba Logic

| | Sherwood Scuba Logic| Price: $490.
Mounting Options: Console, wrist, hose, BC.
User control: One push button.

Thumbs Up: Budget-priced; Easy-to-see numbers; A descriptive dive plan graph; Three-color highlighting; Handles multilevel repetitive diving well; Easy-to-adjust no-decompression limits at any time with use of a graph; Excellent owner's manual; Excellent underwater backlighting; User-replaceable batteries.

Thumbs Down: Hard to read yellow type on the green oxygen bar; Difficult switching to alternate screen under water--diver has to push and hold; Defaults to 50 percent oxygen when in nitrox mode; Time to fly is an arbitrary countdown; Label lettering and certain icons are small.

Multicolored screen prompts, bold numbers and intuitive graphics make the Logic a favorite among both compressed air and nitrox divers. It's an extremely easy computer to follow for nitrogen loading, watching oxygen limits and ascent rates. Simply stay in the green zone if at all possible, back off if you find yourself slipping into the yellow zone, and avoid the red zone.

A single push-button control gives you access to six dive mode screens and one oxygen percentage setup screen. "Lumibright" backlighting illuminates the screen at depth for as long as you press the button--plus 10 seconds. You get a 12-dive internal logbook, a bold nitrogen bar graph and oxygen "bubble" bar graph, an ascent display and visual alarms. Available as a wrist mount, a hose mount and capsule-only.

A full-function nitrox computer, the Logic offers a deep diving algorithm that calculates decompression stops to 60 feet and reads depths to 330 feet. The display of dive time remaining when using nitrox is the lesser of the no-decompression limit and the oxygen limit, but the other data are still graphed on-screen.

Two three-volt lithium cells will power the Logic for approximately 50 24-hour periods of activation (depending, of course, on the number of actual dives made). Batteries can be purchased at any electronics store and are user-replaceable.

Suunto Mosquito, Stinger & Vyper

| | Suunto Vyper| Suunto Mosquito
Price: $500.
Mounting Options: Wrist.
User control: Four push buttons.

Suunto Stinger
Price: $760.
Mounting Options: Wrist.
User control: Four push buttons.

Thumbs Up: Compact size; Light weight (Mosquito); Can be used as wristwatch, stopwatch or dive computer; Provides a free-diving mode; PC-downloadable; Huge profile and logbook memory; Display shield and protective boot; A variety of user settings.

Thumbs Down: Unfriendly owner's manual; Barely readable waterproof prompt cards; Difficult control buttons; Busy screens--numbers and icons extremely small; Short battery life.

Suunto Vyper
Price: $450.
Mounting Options: Wrist, console, BC.
User control: Three push buttons.

Thumbs Up: Built-in dive simulator to plan future dives; PC-downloadable; Extended decompression range; Maximum depth alarm; Huge dive profile/logbook memory; Above-average owner's manual; Owner-replaceable battery.

Thumbs Down: Buttons hard to push; Hard to see screen on the surface with shield attached; Difficult to access data while at depth.

Suunto's budget-priced, lightweight Mosquito and its flagship stainless-steel Stinger combine the compact size of a common wristwatch with all the benefits of a full decompression dive computer. In the surface mode, they offer a calendar clock, dual time, a stopwatch and an alarm clock. Put them in one of their three diving modes (compressed air, nitrox or free diving) and you are served a wealth of diving information.

The advantage of having such a compact dive computer does come at a potential price. Displays are small, and the four buttons tend to be difficult to depress when wearing gloves. It's also not self-evident what button combination yields what diving information.

These Suunto dive computers offer the most extensive memory and dive history available among today's dive computers. A full 36 hours of diving can be profiled in 20-second intervals. You can download this data to a PC using a special Suunto interface package. The Mosquito reads to a maximum depth of 330 feet and the Stinger to 495 feet.

The Stinger offers two customizable screens that allow you to choose what the computer displays during the dive. Clear blue backlighting activates automatically when dive alarms go off so you get a sharp screen picture. It is also available in solid titanium, which is about 30 percent lighter than the standard stainless version.

Both models are powered by one three-volt lithium cell which offers a six- to 18-month operating life, depending on dive activity. The power cell in the Mosquito can be user-replaced but the Stinger's cell must be replaced at the factory.

Like the smaller Stinger and Mosquito, Suunto's larger format Vyper offers three operating modes for compressed air, nitrox or free diving. A handy feature is the built-in dive simulator, which allows you to profile projected dives to make sure they can be accomplished within safety limits. It can also be programmed to activate visual and audible alarms when a dive's preset limits like maximum depth are reached. The Vyper has an automatic safety stop countdown as well as a multistep ascent-rate indicator. The difficulty lies in accessing all these great features while at depth.

The Vyper offers an astonishing 36 hours of logbook memory that can either be read from the display or downloaded to your PC. It comes with electroluminescent illumination, which lights up automatically when an important alarm is triggered.

The owner's manual for the Vyper is far superior to its Mosquito and Stinger cousins, with lots of large graphics and simple instructions. Its single three-volt cell can be user-replaced, adding to its overall convenience. Available as a wrist unit with a protective boot or as part of a two- or three-gauge console.