The Geology of Belize’s Great Blue Hole

Great Blue Hole pic
Great Blue Hole pic
Great Blue Hole

Since 2002, Dr. Stu Steinman has treated patients at WestSports Medicine, a sports medicine practice in Norwalk, Connecticut. Recreationally, Dr. Stu Steinman enjoys traveling and scuba diving. One of his favorite trips involved diving the Great Blue Hole in Belize, one of the most famous dives in the world.

The walls of the Blue Hole limit the amount of sunlight that can enter the water, and poor air circulation creates a scarcity of nutrients. At a certain depth, water in the hole becomes anoxic. As a result, not much marine life lives in the hole.

The real reason to dive the Blue Hole is not the wildlife, but rather the geologic features. The Blue Hole, created by the collapse of an underwater cavern, is seen from above as a dark navy circle in the otherwise aquamarine water.

A degree of stark beauty exists in the hole’s geology. As divers descend, they begin to see coral life fade as the light dims. They pass beautiful limestone formations and eventually hit a thermocline, a point at which the temperature drops significantly. Just below that is a gaping entrance to a recessed cave, the mouth of which is surrounded by 6-meter stalagmites and stalactites. At this point, divers start to understand the draw of the Blue Hole.