By Steve Macnaull - The Canadian Press
At Dean's Blue Hole in the Bahamas it is completely natural to feel scared, excited, fascinated, confused and awed - all at the same time. You see - true to its name - it's a magnificent dark blue circle of water that plunges more than 200 meters into an abyss.
Usually blue holes, also known as sinkholes, simply look like ponds, but Dean's is special.
Connected to the Atlantic Ocean by a light blue inlet, it is framed by scooped-out cliffs on one side and perfect arches of white sand beaches on the other. As the deepest blue hole in the world it attracts sightseers, curious beachgoers, amateur snorkellers, brave scuba divers and free divers.
Our affable tour guide, Sanfred Rolle, certainly knows how to build blue-hole drama.
"I explain it to everyone on the drive here. But you never believe it until you see it. It becomes the highlight of everyone's trip."
First we hike to the clifftop to marvel at the perfect dark circle of water that marks the hole. Then it's time to get in the water.
From the beach in snorkel gear the initial swimming is through shallow water filled with darting fish.
The shallows, white sand bottom and fish abruptly disappear as the hole immediately plunges to 202 meters and the water takes on an eerie but calming, presence.