For divers, this is a must. The great Blue Hole was first made famous by ocean explorer Jacques Cousteau in 1970, who declared it one of his top ten diving sites in the world. Just off the coast of Belize, it’s part of the Belize Barrier Reef, a series of coral reefs 190 miles long, protected by UNESCO. Created by limestone formations over thousands of years, the naturally-occurring wonder is home to crystal clear waters, stunning stalactites and incredible sea creatures. You can scuba dive or visit by boat and the sinkhole itself is over 125m deep. The deep, cold waters are for serious divers. We were lucky enough to see hammerhead sharks, colourful parrotfish and spectacular coral on our dive and there’s always time to feed the sting rays back on the reef.