The Catalina Islands are a small archipelago 10–20 minutes offshore from Flamingo by boat, and they are among the best dive sites on Costa Rica's Pacific coast. The rocky formations create habitats for spotted eagle rays, white-tip reef sharks, moray eels, and dense schools of tropical fish. Visibility ranges from 10 to 25 metres depending on season, with the best conditions generally between November and April.
Dive operators in Flamingo run morning departures to the Catalinas, with options for both certified divers and snorkellers. The snorkelling is excellent in the shallower areas — the islands are close enough to the surface that good coral and fish life is accessible without tanks. A full day trip typically includes two dives or snorkel sessions, lunch on the boat, and a look at the seabird colonies on the island rocks.