Baia do Sancho, Brazil

Baia do Sancho sits on Fernando de Noronha, a volcanic archipelago 350 kilometres off the northeast coast of Brazil, accessible only by small aircraft or boat — and only 460 visitors are permitted per day. The beach is entered through a narrow cleft in a sheer lava cliff via iron ladders bolted into the rock, descending to a crescent of fine golden sand framed by emerald waters so clear you can see spinner dolphins and sea turtles from the shoreline. It has ranked first or second in TripAdvisor's global beach rankings every year since 2015. Best time to visit: August to December.