From the boat, Blue Hole looks rather innocuous—the color of the water changes to a deeper blue, but that is nothing new. To travel the crystal Caribbean waters of Belize is to experience nearly every shade of blue from azure to navy, turquoise to royal.

To slip into the water at the edge of Blue Hole – fins, mask, and snorkel donned – is to experience an unease that can only come from facing the unknown. There is much to be gleaned from a change in blue hue.

From the shallow waters surrounding the hole, where nurse sharks slip around soft corals waving with the gentle swells, the sandy bottom slips away – ten feet, twenty, thirty…four hundred! It happens all at once. There is something beneath you…then there is nothing.

Snorkeling above the rim of this thousand-foot-wide sinkhole, one cannot help seeing whether there are or are not hammerhead sharks lurking in the rapidly enveloping shadows that only depth can create.

Free diving to the top of the precipice – bringing the void up close, if you dare – is a challenge this writer cannot resist. A couple deep breaths, and I point my head down, kicking with my fins until, twenty feet down, my ears hurt. Squeezing my nose, I breathe out, feel a release, and kick on. Just below the rim, perhaps forty feet below the surface, I look at the wall where a lionfish hides in a small grotto. Looking down, I see…dark blue nothing.

Looking up at my fellow snorkelers, appearing tiny on the surface, I give a swift kick and am soon back on top. I had seen enough. I can’t wait to go back and see more!