Cocos Island · Liveaboard
Undersea Hunter
Cocos Island dive liveaboard from Puntarenas
Undersea Hunter runs multi-night dive expeditions from Puntarenas to Cocos Island National Park, about 312 miles offshore. Its 115-foot Sea Hunter is the boat on the Cocos run right now, and the trips suit experienced, well-insured divers who want hammerheads, tigers and open-ocean diving.
What they offer
Undersea Hunter is one of the operators that has been taking divers to Cocos Island the longest. Cocos sits about 312 miles off the Pacific coast, it's a national park and a UNESCO World Heritage Site (since 1997), and the only practical way to dive it is from a liveaboard. You sleep, eat and refill tanks on the mothership, then ride smaller skiffs out to the dive sites around the island.
The company still posts trip reports for its 2025 and 2026 departures on its own site, so this is a working operation, not a legacy name.
The boats
Sea Hunter is the vessel doing the Cocos trips now. It's a 115-foot steel boat with 10 cabins for up to 20 guests and a crew of 10. Cabins have private bathrooms and air conditioning, and there's camera storage with power, rinse tanks for camera gear and an indoor lounge plus sundeck. Nitrox is available on board, and rebreather divers can get oxygen and diluent service if they bring their own units.
Argo, the larger sister ship (about 130 feet), is away on a long expedition with a National Geographic ocean research program, and the company says it won't be at Cocos for the foreseeable future. The DeepSee submersible that used to go out on Argo has been retired, so don't plan around it.
The diving itself happens from 24-foot hard-hulled fiberglass skiffs with twin outboards, a T-top for shade, VHF radio, oxygen and first aid. Each takes up to 10 divers plus 2 divemasters and a pilot, and your gear stays on the skiff for the whole trip, so there's no hauling tanks back and forth.
Where you leave from
Trips leave from Puntarenas on the Gulf of Nicoya. On day 1 the company collects guests from set hotels in San José and drives them to Puntarenas, a ride of roughly 2.5 hours. If the tide is low, you may be ferried out to the boat by skiff. Then comes the open-water crossing of 32 to 36 hours. On the way home you land back in Puntarenas and get driven to San José. The company recommends arriving in San José at least a day early and staying an extra night before flying out.
Who it suits
This is serious diving. Cocos is known for schooling scalloped hammerheads, whitetip reef sharks, tiger sharks, Galápagos sharks, eagle and marble rays, and the chance of whale sharks and mantas. Currents can be strong and the water is open ocean. You'll be happiest here if you're a confident diver with solid buoyancy and some current experience. It's also popular with photographers and filmmakers.
Sailors who just want to see Cocos from the deck should know that these trips are built entirely around diving.
Good to know before you book
- Dives are kept within recreational limits: no decompression diving and a maximum depth of 100 feet (30 meters). Nitrox helps a lot here.
- You need valid Divers Alert Network (DAN) insurance. The nearest hyperbaric chamber is in San José, about 36 hours away.
- Bring a dive computer (mandatory), regulator, BC, mask, fins and a 5 mm wetsuit. Rentals are available.
- Every diver gets a safety kit with a surface marker buoy and whistle, plus a Nautilus GPS Lifeline locator.
- The company may add a fuel surcharge if Costa Rica's diesel price rises past a set level, collected on board.
For more on the island itself, see the Cocos Island section.
Frequently asked questions
How long is a Cocos Island trip with Undersea Hunter?
Most departures are around 10 nights, with some longer ones. Roughly 3 days go to the crossings, and the rest are dive days at the island.
Can beginners dive Cocos?
It isn't a place to learn. Conditions can include strong currents and deep blue-water dives, so you'll want real experience before you go.
Is the DeepSee submarine still running?
No. The company says the DeepSee has been retired, and the Argo, which carried it, is currently away from Cocos.
How many dives a day do you get?
Usually 3, at around 8 am, 11 am and mid-afternoon, depending on conditions.
