It it hard to tell, but it appears that the tail flukes are vertical, not horizontal, which would make it a shark.
It it hard to tell, but it appears that the tail flukes are vertical, not horizontal, which would make it a shark.
The shark is a "water breather", the dolphin is an "air breather". I doubt if the shark would risk the beaching that could occur with such frolicking in the waves. I would guess sharks would avoid waves this close to the shore. Dolphins are rather playful, and would enjoy this activity. Looking again, you'll notice the creature is slightly "nosed down" and rotating slightly to the left, which would account for the appearance of a vertical tailfin (shark). With a shark of this size, the dorsal fin would, I suspect, be much bigger. Also, a shark dorsal fin is more "triangular", the dolphin dorsal fin is more "streamlined" for lack of a better term. Still not convinced? (R) click the image and on "properties"....
Dolphin!