Submerged Rock is one of the remote Cocos Island dives where the plan should follow the ocean rather than a fixed promise. The main attraction is the volcanic underwater landscape and the possibility of seeing whitetip reef sharks, scalloped hammerhead sharks and passing schools of fish. With a maximum planned depth of about 43 metres and moderate | strong current, divers should be honest about their experience and listen closely to the guide’s briefing.

A liveaboard is the only practical way to dive here because Cocos Island lies more than 500 kilometres from mainland Costa Rica. Staying on the island for several diving days also lets the crew choose the site when tide, current and animal activity are most promising. Cocos operators currently do not offer night diving, so the value of a liveaboard here is repeated daytime access rather than night dives.

It combines well with Shark Fin Rock, which gives a useful contrast in terrain and exposure. Water temperature and visibility can change quickly around thermoclines, so a dive computer, surface marker buoy and a 3–5mm wetsuit are sensible even when the surface feels warm. Nitrox is useful on repetitive diving days for suitably certified divers.

For an operator’s description of the sites and practical expedition conditions, see this Costa Rica diving guide. You can also compare Costa Rica diving and liveaboard options before choosing an itinerary.