The ‘Dragon Hole,’ located in in the South Chin Sea, is the deepest blue hole on the planet. At 987 feet, t’s so deep it could even swallow the Eiffel Tower whole. Thought the hole has been known about for centuries, the depth has just recently been determined.
Blue holes are basically just massive underwater sink holes that can plunge down to incredible depths. They get their name from the the vibrant blue colors that can be seen from above them on the waters surface.