I have no idea how an actual DC explosion would look like, but from the following video we can make ourselves an idea of what an underwater explosion seen with the naked eye looks like, compared to what can be seen at slow motion:
The slow motion reveals an expansion phase followed by a compression phase, both accompanied by a "ball of fire"; the sequence ends with a second, smaller, expansion. Everything happens way too quickly for the human eye to register the full sequence though. At least for the type of explosion show in the video, all you can see at normal speed is a cloud of bubbles popping out from the center of the explosion and then disappearing
