Creature from the Black Lagoon?
http://www.imdb.com/gallery/ss/0046876/Ss/0046876/3.html?path=gallery&path_key=0046876
Granted the original movie from the 1950's was bad, but did they producers just grab the costume out of the prop shop and think... YAY our alien?!
Very odd little movie... I really wouldn't bother.