Experience Cocos Island and its abundant marine wildlife while contributing to crucial research on a 10-day expedition aboard the MV Argo,  a comfortable and stylish live-aboard dive vessel.

Cocos Island Expeditions will take divers to experience some of the most spectacular opportunities to view and photograph the incredible marine biodiversity of the East Pacific, as well as participate in crucial research to protect these treasured waters.

The Site

Recently named the best place to dive with sharks by CNN, Cocos Island National Park and World Heritage site is located 530 kilometers southwest of Costa Rica’s mainland. It is known worldwide as an ocean haven for spectacular sharks, rare sea turtles, whales and abundant marine wildlife. Divers will experience the Park’s large populations of scalloped hammerhead and white tip reef sharks, and a number of endemic fish that occur nowhere else on the planet.

The Vessel

Dive participants will spend ten days aboard UnderSea Hunter’s newest vessel, the MV Argo, a beautiful 130-foot live-aboard dive vessel for up to 18 passengers and a crew of 14, where a comfortable and stylish lounge, dining area, and sun deck comprise the social areas. A well-equipped galley enables the ship’s chefs to prepare fresh, international level, four-star cuisine. Three, powerful, fumeless 24-foot skiffs serve as tender-boats.

The Argo sometimes carries a three-person submersible that may be available (at additional cost) for participants who wish to explore deep depths. To see amazing 360 degree views of Cocos Island, the Undersea Hunter vessel and underwater views from the DeepSea submersible, click here.

The Diving & Research

Led by Turtle Island Restoration Network Founder and Director Todd Steiner, biologist and respected conservation leader, expedition participants will join three fantastic dives each day, enhanced through work with Turtle Island biologists to study sea turtles and sharks. Participants will be able to assist with various levels of research depending on experience, diving among schooling hammerheads, several species of sea turtles, and schools of thousands of fish as they support conservation efforts directly at the site. Every evening, participants can enjoy engaging conservation lectures and socializing with fellow ocean lovers.

Research conducted on Cocos Island Expeditions for the past 10 years has set the basis for better protections at Cocos Island and for a protected swimway to save sharks, sea turtles, and other migratory animals as they swim throughout the region.

Most of the action is at 60-90 feet (18-27 meters), and most dives are between 60-130 feet (18-40 meters). The average temperature is 79°F to 84°F (26°C to 29°C), although it can be a few degrees lower under the occasional thermocline.

Hammerheads are easily viewed at close range at “cleaning stations,” and inquisitive green sea turtles commonly approach our dive teams, offering fantastic photographic opportunities and facilitating tagging studies. Other regularly observed species include Galapagos sharks, black tip sharks, silky sharks, marbled rays, eagle rays and bottlenose dolphins. Whale sharks, the special treat of any diving expedition, are also occasionally observed. Endless schools of jacks also swarm the island.

The expedition will be supported by the experienced and well-known dive company Undersea Hunter S.A, which has been operating expeditions to Cocos Island since 1990. The company is committed to top-notch dive experiences, vessels and service, and has operated expeditions for National Geographic, Sylvia Earle, and many other world-renowned ocean explorers and conservationists. Click here to read about Undersea Hunter’s commitment to safety. Participants will be divided into two dive groups which will each be under the supervision of an experienced Undersea Hunter Divemaster/Rescue Diver.

Dive Requirements

The minimum required level of certification to dive at Cocos is Open Water. Divers must be experienced divers, with PADI or NAUI membership, and must have personal DAN insurance. Nitrox is available for certified divers, and certification is also available on the vessel. For more information about required certifications, please contact our trip leader Todd Steiner at tsteiner@seaturtles.org.

View Upcoming Expeditions

Trip Reviews

What an adventure! This is my second time to Cocos Island and this time even more amazing that the first time. Being involved with Ocean Conservation and having an opportunity to assist with the shark and turtle tagging was pure joy. I came on this trip not knowing anyone, and leaving with lifetime friends, beautiful pictures, and stories that I will be sharing back home.

Janet ThomasUnited States

The experience on the DeepSee was an eye opening trip! It is a unforgettable memory through our life. Felipe our pilot is very experienced, funny and knowledgeable; thus we enjoyed the ‘ride’ with him a lot. Especially the gliding mobula rays that played with us more than 10 minutes. DeepSee Rocks!

Pinky & Claus WieslochGermany

Great fun to join the PRETOMA & TIRN expedition for yet another trip. Fantastic as always. Wildlife underwater is great. Crew above water is equally wonderful.

Mike and Nonie SilverUnited States

It was splendid!! I felt very happy, and very safe. Great dive masters. Everything is thought through very carefully on this boat to make guests comfortable. Extremely efficient and hard working crew. Would definitely recommend this live aboard.

Bill WhitmarshUnited States

First class operation, as always!! The crew was outstanding – very professional, helpful and fun. This was the vacation of a lifetime, and I will definitely be coming back again next year.

Deborah KearneyUnited States

Another fantastic trip on the Argo – my third on the boat and fifth with the UnderSea Hunter family. The vis wasn’t as good on this trip as it’s been on past trips, but there were still sharks to be seen and turtles to be caught and tagged. The trip companions were fabulous, and the crew was outstanding as always. A big thanks to Rafa for keeping track of us while we were below the water – a welcome sight to surface to. Bryan and Yoyo were great dive masters and Javier was always smiling. I’ll be back.

MarkUnited States


Photo by Kevin Weng

Report: Volunteer Divers, Scientists Tag Sharks on December Cocos Expedition

| Cocos Island, Cocos Island Research Expedition, Eastern Tropical Pacific, Sea Turtles, Sharks | No Comments
In December, a crew of volunteer divers, marine biologists, scientists, and dive masters joined Turtle Island Restoration Network (TIRN) on one of the organization’s yearly research expeditions to Cocos Island…
Using scuba and a six-foot pole spear, Turtle Island Restoration Network's Executive Director Todd Steiner placed an acoustic transmitter below the tiger shark's dorsal fin in order to monitor its habitat use at Cocos Island National Park. The tag will monitor the shark’s movements for two or more years. | Photo by Turtle Island Restoration Network.

Bay Area Scientist Successfully Tags Aggressive Tiger Shark Linked to Diver Death in Costa Rica

| California, Cocos Island, Cocos Island Research Expedition, Headquarters, News Releases, Sharks | No Comments
Using scuba and a six-foot pole spear, Turtle Island Restoration Network's Executive Director Todd Steiner placed an acoustic transmitter below the tiger shark's dorsal fin in order to monitor its…

TIRN Awards Scholarship for Upcoming Cocos Island Research Expedition

| Cocos Island, Cocos Island Research Expedition, Cocos-Galapagos Swimway, Eastern Tropical Pacific, News Releases | No Comments
Olema, CA — Turtle Island Restoration Network (TIRN) has awarded a scholarship to an early career marine conservationist who will help TIRN study, tag, and track sharks and sea turtles…

Shop Online. Save Sea Turtles.

| Cocos Island Research Expedition, Got Mercury?, Marine Mammals & Seabirds, Sea Turtles, Sharks | No Comments
The holiday's are just around the corner and if you are like me you are starting to think about what gifts to give to loved ones during winter celebrations. This…

TIRN Announces Second Conservation Scholarship Winner for 2017 Dive Expedition

| Cocos Island Research Expedition, Headquarters | No Comments
For the first time ever, Turtle Island Restoration Network (TIRN), a global marine conservation nonprofit, has offered two scholarships to early career marine conservationist for its yearly Cocos Island Research…

TIRN Announces Conservation Scholarship Winner for 2017 Dive Expedition

| Cocos Island Research Expedition, Headquarters, Sea Turtles | No Comments
For the first time ever, Turtle Island Restoration Network (TIRN), a global marine conservation nonprofit, has offered a scholarship to an early career marine conservationist for its yearly Cocos Island…