Cocos Island (locally Islan Dåno'), a small uninhabited island off Merizo in southern Guam, sits inside its own barrier-reef lagoon and is widely rated the island's best snorkeling spot — its coral is in noticeably better shape than Tumon's, and 100+ foot (30m) visibility is common in the calm, shallow water. Depths inside the lagoon run about 1-5m over healthy hard and soft coral, with green and hawksbill turtles a near-guaranteed sight and the occasional lucky encounter with dolphins or a manta ray. As of July 2026 the island still runs as a day resort reached by a short ferry from Merizo Pier, and the lagoon overlaps the Achang Reef Flat Marine Preserve, so nothing may be fished, collected, or taken from the water.
Calm, shallow Cocos Lagoon ringed by a barrier reef, with 20-30m of visibility
Healthier coral and reef fish than the more crowded reefs of Tumon Bay
Regular green/hawksbill turtle encounters; occasional dolphins or manta rays for the lucky
Short ferry ride straight from Merizo Pier to Cocos Island Resort (pool, restaurant, gear rental)
Gentle, family-friendly entry, plus kayaking, jet skis, banana boats, and parasailing for non-snorkelers
Good to know
SafetyCurrents build fast once you're past the marked lagoon area, near the outer channel or reef edge — rip and longshore currents there can sweep swimmers toward open water. Stay inside the marked swim zone, snorkel with a buddy, and use a float or vest.
SafetySharp coral, sea urchins, scorpionfish/stonefish, and cone shells can cause serious cuts or stings. Wear reef shoes, never stand on coral, and don't handle any shell with bare hands.
SafetyJune-August (July especially) is Guam's peak box jellyfish season. If stung, rinse with vinegar rather than fresh water and scrape off tentacles with something rigid, not your hand.
SafetyThe resort area shares water with jet skis, banana boats, and parasail boats. Snorkel only inside the designated lagoon zone and stay alert to boat traffic.
RulesThe lagoon overlaps the Achang Reef Flat Marine Preserve: no fishing, collecting, or taking coral, shells, or any marine life, and Guam-wide law bans coral harvesting in 60ft (about 18m) of water or less. Use reef-safe sunscreen.
MannersKeep a respectful distance from turtles and other wildlife — no touching, chasing, or feeding — and never stand or kick fins onto live coral.
SeasonGuam's rainy/typhoon season runs roughly July-November, peaking August-September, and can force ferry cancellations on short notice; the December-June dry season generally brings calmer seas and better visibility.
Practical info
Access is a short ferry ride from Merizo Pier to Cocos Island Resort, where you rent gear and enter the lagoon directly; sailings can be cancelled on short notice during typhoon season (Jul-Nov), so confirm current ferry schedules, fares, and any tour/booking requirements before you go.
On-site reviews📍 Verified on-site
No reviews yet. If you are here, be the first to leave one.
