Reef

A reef is a living underwater structure built over thousands of years by coral polyps. The three main types are fringing reefs (right against the shore), barrier reefs (further out with a lagoon between them and land, like Australia's Great Barrier Reef or Belize's), and atoll reefs (ring-shaped). For travelers, the key question is whether your resort has a healthy house reef, meaning corals reachable by swimming from the beach. A great house reef means free unlimited snorkeling. Climate change has caused major bleaching events (2016, 2024), so look for resorts running active coral propagation programs as a sign of long-term commitment.