Okeanos Aggressor I and Okeanos Aggressor II

A voyage to Cocos Island, Costa Rica, is on every diver’s dream list, thanks to its big-animal bounty. For starters, it’s famous for schools of scalloped hammerheads numbering in the hundreds. That’s right, hundreds. Seeing the sun blotted out by so many powerful ancient predators is easily one of the most life-changing experiences a diver can hope to have.

Encounter schools of hammerheads on Cocos Island.

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Hammerheads frequent these waters as Cocos Island is the northern point in what’s known as the Golden Triangle, aka a hotspot where these animals concentrate, migrating between points; the other two are the Galapagos Islands of Ecuador to the southwest and Malpelo Island off Colombia to the southeast.

So remote, 342 miles west of Costa Rica, the volcanic Cocos Island, with its underwater sea mounts and pinnacles, serves as an oasis that attracts leagues of big animals, in addition to the hammerheads. Ten species of shark are found here, including silky, whitetip reef, silvertip sharks and more.

Whale sharks are often spotted during the rainy season.

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And of course, whale sharks. During the rainy season, June through December, the waters become thick with plankton, which attract the world’s largest fish, spanning 40 feet. This season is also when the largest numbers of giant mantas are seen resting at cleaning stations, and flying endless loops as they siphon up plankton. Out here, you’ll also witness schools of tuna and jacks descend upon the group like curtains, obscuring the view of the divers to either side.

Bottlenose dolphin sightings are also common mid-dive, and on occasion, so are short-finned pilot whales and humpback whales. Moreover, because so many big animals are prevalent in big numbers, divers also get the chance to witness interactions between several species at a single site, which is a unique component of the Cocos experience. At one site, you might witness hammerheads at a cleaning station, while yards away, dolphins feed on schooling sardines.

The Okeanos Aggressor I

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Of course, as is often said of the ocean, anything can happen, but diving in Cocos is like playing with a stacked deck. It’s the type of place where every dive feels like the most thrilling yet.

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Both Okeanos Aggressor I and II divide their time between two itineraries in addition to Cocos Island. Cano Island, also off the west coast of Costa Rica, is a wonderland where what you’ll encounter daily — be it giant mantas, marlin, eagle rays, dolphins, pilot whales, blacktip sharks and more — can vary greatly thanks to tidal swings that fluctuate quickly.

You’ll spot a variety of different marine life daily in Costa Rica.

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The third itinerary targets Guanacaste and the Bat Islands, home to a sweeping area of diverse ecosystems. On this itinerary, not only will divers encounter big animals, including mantas, marble rays, mobula rays, sharks and large schools of fish, they’ll also lay eyes on frogfish, and an array of other macro finds. Daily sightings can range from 30-some eagle rays, to an encounter with a 23-foot-wide giant oceanic manta, lasting 20 minutes.

Moreover, because these locations are still so far off the beaten path, groups won’t encounter other vessels, but rather, will have the ocean to themselves to explore.

NEED TO KNOW

Home Port: Puntarenas, Costa Rica
Dive Season: Year-round in Cocos; the yachts’ rotations include weeks at Guanacaste and the Bat Islands
Water Temperature: 75–86˚ F
Travel Tip: If you prefer flatter seas and better visibility, travel December through May. However, June through December is the rainy season, when nutrient upwellings lure in the big numbers of hammerheads, whale sharks and mantas.