Thanks for your comments, guys. OK, I'll find something else instead of the transporter or tint it differently. No idea yet.
@inky: there is actually a (barely visible) boat.
@Ulco: great idea, I'll play with the lighting and some mist.
In this crop render the boat seems to stand on top of the water. Actually it's lying in the sand, but since there is a reflective layer on the sand to represent the wet area near the water's edge it looks a bit weird. Gotta fix that too.