Scuba diving Cocos Island

The reefs, submerged volcanic landscapes, and deep, nutrient-filled ocean waters around Cocos Island are home to over 300 species of fish (including more than 25 endemic species such as the striking, rosy-lipped batfish), corals, and crustaceans, but it's the astonishing volume of pelagic life that has made scuba diving in Cocos Island world famous.

May to November is the best time for diving with the huge schools of scalloped hammerhead sharks, while the biggest fish in the sea, the whale shark, only hang around from May to August, feeding off the local plankton.

Manta rays enjoy the waters for the other half of the year, from November to May, but, really, any time of year is good for checking out the huge populations of yellowfin tuna, marlin and sailfish

Throughout the year humpbacks, pilot whales and dolphins can be spotted passing through the region, as well as a variety of turtles, including hawksbill, green and olive ridley turtles.

Manuelita Coral Garden is often the first dive spot on Cocos Island trips. With generally calm ocean conditions, the garden ranges in depth from 6 to 21 meters (20 - 70 feet) filled with numerous tropical fish, lobsters, eels, as well as the big stuff such as black and white tip sharks, turtles, eagle rays, hammerheads, and even the occasional tiger shark. If that weren't impressive enough already, a night dive here boasts massive schools of white tip sharks weaving through coral formations in search of food.

For scuba diving with hundreds of scalloped hammerhead sharks, Bajo Alcyone cannot be beat. Positioning themselves at 25 meters (82 feet) atop a massive, undersea mountain, divers hang on amid the strong currents as they are practically swarmed by hammerheads, while enjoying visitors to the local cleaning station including mantas and mobula rays, and keeping their eyes open for passing free-swimming moray eels.

The huge natural arch at Dos Amigos Grande is a thing to behold and adds an adventurous and interesting aspect to your dive.

Consisting of rock pinnacles and volcanic boulders that break the surface of the Pacific, Dirty Rock is also one of the best dive sites in Cocos Island for checking out an unbelievable volume of schooling hammerheads sharks, as well as silkies, eagle rays, immense schools of jacks and the occasional whale shark.

Silverado is a wonderfully shallow dive site off Cocos Island where silver tip reef sharks seem to line up patiently for their turn at the local cleaning station on top of a two-meter-high pinnacle. Divers relax on the sandy bottom at 13 meters (40 feet) and watch the shark action unfold before them.

Off the southeast coast of Cocos Island, Submerged Rock, as its name implies, sits just below the surface, only visible from above at certain times, and presenting a well-known hazard for boats. This flat-topped pinnacle offer divers colourful scenery and a small, arched swim through abounding with a manner of tropical, tuna, hammerheads, mobula rays and often pregnant mother white tip sharks with their miniature offspring.

The weather on Cocos Island is humid and tropical all year long, with plenty of rain showers to keep the island eternally lush and green, and temperatures on average around 33°C (92°F) during the summer months of May to November dropping to around 27°C (82°F) in the winter, or invierno. Although the island still has a wet and a dry season like mainland Costa Rica, it rains pretty much most days.

Water temperatures are fairly consistent throughout the year, only changing by a degree or two from summer to winter, staying in the range of 24-28°C (76-82°F). But because the island is basically out in the middle of the deep Pacific waters, temperatures can also vary from site to site and thermoclines are common, so many people diving in Cocos Island bring along a hood, gloves and booties to compliment their 3 to 5 mm long wetsuit.

Visibility at dive sites is best during the drier months of December through April (up to 25 meters / 85 feet), and currents generally at their gentlest, offering divers the chance to see an impressive array of marine species. But most divers opt for the more challenging ocean conditions and lower visibility encountered from May to November for their Cocos Island dive trip, as they're here to see the schools of hundreds of scalloped hammerhead sharks.

Along with these stars of the Cocos Island show, Whale Sharks are also in residence from May to August, while diving during the months of November to May increases the chance communing with Manta Rays. The New Year brings migratory humpback and pilot whales into the area.

The scuba diving in Cocos Island can be challenging thanks to ocean currents, surge and deep diving, and some liveaboards ask for divers to be certified Advanced Open Water with 50 logged dives, but there are plenty of opportunities for diving in Costa Rica as an open water diver, or even just snorkeling, and availability to upgrade to an advanced certification during your dive trip. In addition, divers have the chance to dive nitrox and rebreathers.

The easiest and most comfortable way to scuba dive Cocos Island is from a Costa Rica liveaboard. The main airport serving international arrivals into Costa Rica is Juan Santamaria Airport (SJO), 17km (11 miles) northwest of the country's capital of San Jose, but quite a few Canadian and US airlines are now also flying into the norther airport in Liberia - Daniel Oduber Airport (LIR).

From either entry airport, it's about a 2 hour ride through the farmlands and plush native jungle to the port city of Puntarenas, the main jumping off point for scuba diving liveaboards in Cocos Island. Sailing from Puntarenas, liveaboards sail overnight 32-36 hours out to the spectacularly remote Cocos Island to discover the incredible wonders this unique dive area has to offer.