Sinkhole Diving. A sinkhole is a no natural external surface drainage in the ground. It's often a collapsed limestone cave with an open top and a large open water area. You can see the daylight over your head. The sinkhole has a large passage that allows two divers through side by side without any restrictions.

Cavern Diving. Generally speaking, cavern diving is usually a daytime underwater activity, which takes place at the mouth of a cave. While you have entered a closed cave with overhead obstacles, but you can also see the natural light. Sometimes it's very faint, you must turn off the dive torch to see it. The faint light can guide you to return to the entrance, then to the open water. 

Cave diving is an advanced technical underwater sport, different from cavern diving, it takes place in a completely enclosed dark space were without any natural light. Therefore you must use a canister dive light which is special for cave diving to help you. The cave is a closed body of water that contains silt, dark areas, and narrow passages, which are sometimes not enough for two divers to through side by side. This is different from sinkhole diving and cavern diving. 

The key difference among the three is that the difficulty of diving. Cave diving is a specialty qualification that only the top 1% of divers can attain, the other two are an extreme underwater sport. 

Besides, equipment-wise, sinkhole, cavern, and cave divers also differ widely. Only cave diving when you are trained for. Use 1 light (main) light with a canister like the OrcaTorch D630, why? You can hang the light on your neck, and you can use your hands. Longer runtime’s. for Cavern, use 1 backup light (D710), for the cave we need 2 backup lights like D710, Why D710, pushbutton, 3000lm, long runtime.