S/Y CUAN LAW - St. Maarten
“To give you an idea of the water’s clarity, from the dinghy, we saw flying gurnards on the sand 100 feet below,” says Duncan Muirhead of diving Sombrero — a speck of land that’s part of Anguilla and is the northernmost islet in the Lesser Antilles.

It’s just one of the potential stops on the April “Down Island” cruise aboard the S/Y Cuan Law, a luxury sailing trimarin live-aboard owned by Muirhead and his wife Annie, which typically operates in the British Virgin Islands.

The charter departs from St. Maarten, and the itinerary — which varies from eight to 12 nights — also includes Saba, a volcanic island south of St. Maarten. It’s a route not often traveled, except by humpbacks, which often pass between the boat and shore.

Michele Westmorland

M/V POLAR PIONEER - Antarctica
It’s the most challenging — and expensive — continent to check off your must-dive list. Antarctica’s limiting factors add up to a still largely untouched beauty: mountains of brilliant-white ice and turquoise water.

The wildlife is spectacular, and Gentoo penguins, leopard and crab-eater seals, and humpback, orca, and minke whales still approach divers largely without fear. You’ll be captivated by every animal interaction, but during your first in-water seal encounter, you’ll never forget the electricity of the moment.

Come prepared: The unique 11-day journey aboard the M/V _Polar Pioneer_ is designed for those who already possess ice-diving gear and skills.

Courtesy Dive Adventures

S/Y INDO SIREN - Indonesia
Don’t worry: Learning to pronounce the island names is included in the itinerary. Every November, the S/Y _Indo Siren_ departs for the 14-night Banda Sea Discovery trip through Indonesia’s lesser-known dive destinations: Serbete, Gunungapi, the Lu­cipara Islands, Misool and more. Out there, odd and unusual is the everyday.

The Pantar Strait is home to bearded scorpionfish, leaffish and sea apples, a psychedelic-colored variety of sea cucumber. Though is the region is a muck wonderland of tiny creatures, it is also the cruising grounds of big pelagics like mola mola, humphead wrasse, mantas and eagle rays.

Colin Marshall/FLPA/Minden Pictures

M/V NATIONAL GEOGRAPHIC ORION - Spice Islands, Indonesia
“We won’t be going to any known dive sites,” says Michelle Graves, Lindblad Expeditions’ expedition development manager of the 15-day itinerary that departs the northwestern tip of Kimberley, Australia, for Indonesia’s Spice Islands this August.

The newly outfitted M/V National Geographic Orion will travel to three places that few people visit: the oceanic atolls of Rowley Shoals Marine Park, East Timor, and a remote stretch of Indonesia that includes Komodo and Larantuka.

Charo Gertrudix

M/V SPOILSPORT - Coral Sea, Australia
It’s what coral reefs would look like if human beings had never existed: The wall known as Deep Sea Arcade looks like a coral factory. The vibrant marine-life diversity here is enough to challenge Pantone to a color-off.

This Coral Sea site is the focus of the M/V _Spoilsport’_s exploratory trip, a seven-night itinerary departing Cairns, Australia, bound beyond the continental shelf for the plummeting walls of Holmes, Osprey and Bougainville reefs. You’ll need serious diving credentials to participate:

The trip is aimed toward attracting technical divers and researchers, including nighttime seminars on deep diving, but the payoff is a first-hand experience of a region that few will ever dive.

Simon Mitchell

M/V NAUTILUS EXPLORER - Clipperton Atoll
The question rolls right off the backs of the M/V Nautilus Explorer crew. “Wouldn’t it be easier to run a trip to Socorro?” Easier, yes, says owner Mike Lever. But easy isn’t how adventures begin. The Clipperton Atoll lies 650 miles from Acapulco, Mexico — a two-night steam. “It’s so far off the beaten path, it’s ridiculous,” says Lever, who spent 12 years reading up on the island’s crazed, enslaving lighthouse keeper and the illicit base the U.S. built during World War II.

As for what you’ll find in the water on this 15-night itinerary, it’s hard to say. One thing is certain: You’ll witness green morays writhe from the sea to devour land crabs. The walls aren’t thoroughly mapped yet, which adds to the island’s expeditionary allure. Out where so few people set foot, this itinerary evokes the era of early scuba explorers.

Clifton Beard

M/V DAMAI II - Indonesia to Yap
Alberto Reija Garcia, owner of the M/V _Damai II,_ has no idea what divers will see on the 16-day expedition from Indonesia to Yap departing June 14 — that’s why he invited a local marine biologist.

“He’ll tell us what we are seeing,” says Garcia, “and how the atolls evolve as we progress.” When pressed, Garcia admits he expects to see quite a lot of pelagic action, such as sharks, and gardens of soft corals. Beyond that, he anticipates the surprise. “Exploring like this — it’s the next step in diving.”

Courtesy Dive Damai