Daisetta
Found in Texas, this sinkhole started at roughly six meters in width, but due to the salt dome found beneath the area, erode away to roughly 275 meters wide and 80 meters deep.
Deans Blue Hole
Considered to be the deepest underwater sinkhole, at roughly 200 meters deep, this sinkhole can be found in the Bahamas. It was found that the circular opening widens as you go deeper into the sinkhole. As creepy as this is, the world free diving championship has been held there, where a record of 92 meters was set by free diver William Trubridge.