Aquaman and Namor might get a bad rap for their aquatic powers, but they're both a damn sight better than Stingray.
An oceanographer who comes across Namor in 1967, Walter Newell is about as bizarre as it gets when it comes to the superhero genre, if the red and white winged get-up didn't scream that loudly enough already. The Ray, equipped with a fancy suit that let's him glide around along with other, equally dismal abilities, can also travel really quickly underwater... and that's about it.
He doesn't really do much else during his time with the team. Tony Stark accuses him of using Stark technology to make his suit, which leads to Iron Man's temporary dismissal from the group for a few issues.
There are worse things to lose your Avengers membership over, I suppose.