The Great Blue Hole has a "swimming pool" of water at the bottom - Apparently.
The Great Blue Hole, a massive underwater sinkhole in Belize, has a unique feature: a small, isolated body of water at its bottom. This "swimming pool" is a 300-meter-wide, 150-meter-deep depression surrounded by a wall of limestone rock. It's thought to be a remnant of a freshwater lake that existed above the hole when the sea level was lower. This phenomenon has been studied by scientists and can be verified through satellite imagery and underwater explorations.