Brighten these sprites up a bit...no a lot. The details are completely lost, and the shades are way too close. Really, with shades that close, AA isn't really needed.
I don't see the pillowshading everyone is talking about. It looks like the lightsource is coming from the upper-right hand corner. In the scuba version, a blue tint over the facemask would make it more evident that he's wearing a mask. Or even just a white hilight.
Some hilights on both of them in general would be nice and bring out the form alot more.
These are nice, though. Keep up the good work.