The Batwoman（1968）

A whacked out scientist is capturing wrestlers (because they are "perfect") and using their spinal fluid to create a Gill Man. Two cops call in Batwoman to investigate. She steals aboard the baddies boat , uncovers his mad plan, but she is discovered and during a scuffle our hero tosses acid in the scientists face. This doesn't sit too well with the dude and he seeks revenge. His plan, capture her and turn her into a Gill Woman!