We got shark fin, hat and shark fin straps for shoulders from oriental trading catalog.
Made the shark suit from gray onesie and tights.

Shark victim wore surf shirt with black tights and ripped clothing to look like she was attacked by shark. Used fake blood and scars for her bites.
Made a fake surfboard from cardboard and put a big bite mark in it. Attached it with a big piece of elastic to make easy to carry.

Fun costume for siblings or friends, lots of compliments.