I like your creepy green fellow, I think you should improve upon him, possibly in a new photo or two. Backgrounds enhance a picture. I personally enjoy a smaller image (like yours), but that doesn't mean you can't add detail behind and around the centerpoint, maybe with some plantlife? I don't know, just my thoughts. I also enjoy the sketch-style that you drew him with, I'd say stick with that.
As for the diver, I'd change the background so it isn't completely dark, like the gent above me said. However I think it would look nice in that dark setting, maybe just with a slight mix of colors, deep blue fading into black maybe... possibly even some surreal color like purple, to go with the bright green of his suit.
Anyways there's my two cents, keep up the nifty drawing.