One of Dominica’s most popular underwater playgrounds has you snorkeling amid volcanic bubbles emerging from vents beneath the sea floor and rising up as drops of liquid crystal, making it feel like you’re swimming in a giant glass of champagne. Best of all, you can snorkel right off the (rocky) beach. Technicolor fish and coral abound.

A shop rents gear for US$19 and a small restaurant serves upscale local fare.