Cave Formations

The submarine was about to hit the bottom of the Blue Hole and it was just before when the visibility underwater dissipated. Having said that, soon after a formation appeared and to them which was a clear testimony as to how and what shaped this geological structure. The presence of such hanging stalactites is only possible if the structure had once been located on dry land and formed through water dripping into the cave. This cave structure was 43 miles from any water body, so how did it end up under 400 feet of Ocean?