GASP! There is a stray pixel on the bottom left of the piece! It's inside the blackness.

I like the nice simple stle to this and the emptyness really express the vast ocean. Small query though, what is the red thing?

I like the background the way it is. The different shades for the background objects at different depths is well-done, and the subdued quality of the background draws the eye to the foreground.

 Very good

haha hillarious.

Nice idea!!

 It's good, but work on making the background more in depth, also more shades of blue would be more pleasing to look at. Overall I think it's good just a couple things to work on.