Sharks, dolphins, mantas, sea lions and other big ocean animals are the main attractions at these 10 destinations. If you're looking to encounter plentiful marine life, you can't go wrong with any of these spots.

1. Cocos Island, Costa Rica
The deep Pacific Ocean water surrounding Cocos is swarming with packs of silky sharks, whale sharks and schools of hammerheads. The Equatorial Countercurrent brings a rich array of pelagic marine life. In addition to sharks, there are giant Pacific manta rays and massive schools of jacks. Accessed by live-aboard, the diving off Cocos is for experienced divers: Depending on currents and conditions, you’ll drift or swim along the submerged base of islands or tuck in to the rocky face of a seamount. At Manuelita Island, white-tip reef sharks and giant schools of bigeye jacks provide lots of excitement. Hammerheads congregate near the pinnacles at Dirty Rock and Dos Amigos.

2. French Polynesia (Tahiti and Sister Islands)
These postcard-pretty islands offer pulse-pounding adventure at high-voltage shark sites. The Rangiroa Atoll, just a one-hour flight from Tahiti, offers drift dives with hordes of sharks, jacks, tuna, barracuda and manta rays during tidal changes at Avatoru and Tiputa channels. You’ll encounter silver-tips at Avatoru, and gray sharks and white-tips at Tiputa Pass. From December to March, you might encounter hammerheads at Tiputa, and if you’re lucky, you can snorkel with humpback whales in the Austral Islands Group from July to October.

3. Galapagos
A weeklong liveaboard trip to this renowned archipelago will practically guarantee encounters with the big stuff: manta rays, dolphins, sea lions and sharks. Fueled by clashing arctic and tropical currents, the seas here boil with life. Sharks — hammerhead, bull, silver-tip, white-tip, black-tip, Galapagos and gray reef — swim in packs 50-strong. Rays can also be spotted in dense packs. Off remote Darwin Island, whale shark sightings are possible between May and December. Book a trip aboard the Galapagos Aggressor.

4. Palau, Micronesia
At Blue Corner, Palau’s most famous big-animal site, you simply clip yourself in with a reef hook, put a little air in your BC, and wait for sharks — including black-tips and hammerheads — to pass by. Other big fish like sailfish and yellowfin tuna can also be encountered here. Ulong Channel is a narrow cut through the reef that funnels fish, divers and big sharks together on incoming tides.

5. Yap, Micronesia
It’s estimated that more than a hundred giant Pacific manta rays congregate in Yap’s waters, with the encounters so reliable that divers make pilgrimages to the island just to see the famed devilfish. The mantas are most active during their mating season, December to April. Drawn to the easy feeding in Mi’il Channel’s plankton-rich waters, the mantas tend to congregate at cleaning stations.

6. New Providence, Bahamas
Sharks are the star attraction off New Providence, where regular shark feedings at mid-depth reef sites like Shark Wall, the Arena and Runway pull in an abundance of Caribbean and black-tip reef sharks. But not all shark dives off New Providence involve feeding. Divers have chance encounters with white-tip reef sharks at Lost Blue Hole and with silky sharks at the open-ocean site Shark Buoy. Dive it with Stuart Cove Dive Bahamas.

7. Baa Atoll, Maldives
Baa Atoll in the Indian Ocean is home to one of the planet’s most astonishing encounters. The southwest monsoon season from May to November brings a massive concentration of plankton to this atoll, which in turn attracts huge numbers of whale sharks and manta rays. The Maldives are a hot spot for underwater photographers, and many of the atolls have manta spots. Experience it with the Four Seasons Resort Maldives.

8. North Carolina
During mid- to late summer, breeding sand tiger sharks converge on many of the best wrecks off coastal North Carolina, including the Papoose, Atlas and Caribsea. These ferocious-looking, but docile sharks often come within a couple of feet of divers. Mantas are also sometimes spotted near these wrecks.

9. Bimini, Bahamas
Liveaboards to the Bimini chain seek out the resident pod of Atlantic spotted dolphins at White Sand Ridge on the flats of the Little Bahama Bank. These playful and graceful animals often show off for divers and snorkelers.

10. Gladden Spit, Belize
Dive operators in Placencia, Belize, put divers in the water during fairly reliable whale shark encounters from March to June — which is when the sharks come to take advantage of snapper spawning. Operators plan trips around the full moon and while the encounters are not guaranteed, you can increase your chances of getting close to the world’s biggest fish by booking at these times.