Chris and Jody are masters of the miniature, treasure hunters of the tiny. Both are divemasters aboard Belize Aggressor III, where I’ll cruise Lighthouse Atoll for a week in search of my own marine treasures, both big and small.

I meet the men, along with the rest of the Aggressor crew and guests, at the dock in Belize City. Capt. Jay Roberts has 10 years of experience, and Belizeans Jody and Chris have dived these sites for a combined 20 years, so I know we’re in for an amazing week. Excited guests range from the first-timers (me) to seasoned pros like Wanda and Holly, ages 72 and 73, who’ve been on Aggressor trips all over the world and dive with magnifying glasses — as you can imagine, they’ll become very tight with Chris and Jody.

“Go play in your backyard,” says Chris on our first day, after the initial briefing. There’s a bell on the dive deck, and when rung it means one of two things: time to eat or time to dive, he explains. My dive buddy, Joel, and I are ready to dive, so we suit up and splash in at Dos Cocos, a wall dive on the west side of Lighthouse. Each day the first two dives are at one site; the last three are at another. All are walls, so the only big decision Joel and I must make is left or right. We go right, and drop down to around 70 feet along the wall, seeing lots of barrel sponges, whip coral, butterflyfish and a huge school of jacks underneath the boat on our safety stop. On our fourth dive of the day, at a site called Cathedral, we dive with Chris, who spots decorator crabs, wire coral shrimp and nudibranchs. As enthralling as the little stuff is, nothing can match meeting Bubba, the site’s resident loggerhead turtle, who rises in front of us from the shallows like a leviathan. Hands-down the largest turtle I’ve ever seen — he’s got remoras clinging to his belly and a head the size of my skull — he glides past us with inches to spare before continuing on with his daily routine.

Our days too fall into a pleasant, predictable routine: Jody or Chris rings the bell, and we all move Pavlovian-style to the dining room or the dive deck: breakfast at 7 a.m., dive at 8 a.m. Then it’s snack time, then dive, lunch, dive, snack, dive. Then it’s dinnertime and a night dive. And let’s be clear — when I say “snack,” I mean homemade brownies, chicken wings, spinach-artichoke dip, and desserts like bananas foster with ice cream every night with dinner.

On our fourth day, we hit the site on everyone’s bucket list: the Blue Hole. The excitement on board is palpable. Holly and Wanda remain in the shallows, magnifying glasses in tow, but the rest of us gear up and head down. It takes less than two minutes to drop to 130 feet, where we swim among the stalactites of the sunken cave, whose depth bottoms out at over 400 feet. We see a shark on the way down, but otherwise the dive is remarkable just for the sheer immensity of it — it’s deep, it’s cold and it’s very, very blue. Throughout the week, on dives at Aquarium and Silver Caves, Long Caye Ridge and Painted Wall, we see everything from minuscule pipehorses to Caribbean reef sharks. On a night dive, I spot a Caribbean octopus, which uses the lights from our torches to hunt, as do the gigantic tarpon that school under our boat each night.

When we pull back into the Belize City dock on Friday night, all the guests go to dinner together in the city. A successful live-aboard trip is much like alchemy: stellar diving, a friendly crew, an easy rapport between guests, and the food — the glorious food — all must combine in the right proportions to make for a magical week. Luckily for me, all these factors aligned perfectly on the Aggressor, both big and small.

Read more in our Ultimate Diver's Guide to Live-Aboards and find out more about Belize Aggressor III and other live-aboards.