Batu Bolong is one of my favorite dive site in Komodo National Park. It can be tricky to dive with its strong current but it's still manageable compare to Crystal Rock or Castle Rock.
Depending on the current, we get to dive on both side of the rock. We dove twice here, the first one was in the afternoon on the back side of the rock, the temperature dipped to 23C and it was cold. The second one was morning dive, temperature was 26, the dive was pleasant and we got to dive on the front side where you can see the big hole on the rock above the water. Hole can be translated into 'bolong' in Indonesian language.
The marine life are abundant, with many species. White tip Shark, Baracuda, Sweet Lips, Napoleon, Anthias and many more.
It's a diving and snorkling site not to miss when you visit here!