Great Blue Hole

Great Blue Hole, Belize — a near-perfect 300-meter-wide sinkhole in the Caribbean, one of the world's most famous dive sites, plunging over 120 meters into ancient limestone caverns.

Only certified divers can descend into the hole itself to see its stalactite formations and resident reef sharks, but day trips from Ambergris Caye or Caye Caulker also include snorkeling stops at Half Moon Caye's booby-bird sanctuary. Visibility is best in the dry season, April to June.