Hi deep diver-
Your shots are in focus and seem to be exposed correctly. Their soft points are in the composition. The hawksbill is placed dead-center and has a strange look in its eye. In addition it is swimming straight at the camera. Had you waited a second more, it probably would have turned and put itself at a more amenable angle to show off more of the animal. The other two shots are nice reef shots but seem to be missing a subject. If your subject is the sponge, you should be closer to it and take it from an angle that inspires interest. Like I stated initially, though, they aren't bad pictures; in fact they're pretty good. I just hate it when a critic looks at a picture and says, "nice shot" without giving me any direction to go with it. jIf you want more advice, you might try posting them on a website specifically made for providing criticism such as photo.net.