Funny enough, there is a big difference between what new divers are scared of before they go on a dive and what actually causes people to panic underwater. Before the dive it can be any number of things. Risk of equipment failure. read more
While in the water, however, and probably most relevant to this question, my two greatest fears are losing my group or someone in my group, and coming across a big predator. The first is more avoidable than the second, but not 100%, and coming across a shark still remain the moments that scare me the most. read more
In addition to giving scuba divers the distinct feeling that they're flying through a landscape painting, the underwater river allows them to snap mind-blowing pictures like the series you're looking at taken by Anatoly Beloshchin. read more