Mesoamerican Barrier Reef, Belize to Honduras

As the second-largest barrier reef globally, the Mesoamerican Barrier Reef stretches 1,000 kilometres across Belize to Honduras, anchored by the iconic Great Blue Hole, a marine sinkhole 300 metres across. This reef is 30% longer than the Red Sea Coral Reef (#4), but over 60% of its corals show signs of decline due to coastal development—a rate faster than the average Caribbean reef. Conservation efforts have boosted fish biomass by 20% in protected areas, offering a model for sustainable tourism in the region.