Green algae is off - too much alien green... same with the greener tree - try to match the hue of the other tree. Rocks need to be wet and slime coated where they meet the water, same with the disused boat, that should be sun bleached where not wet, perhaps some depth of field can also disguise the front "barnacles" which dont in effect look like barnacles. Overall is a pleasant scene, but there's no story to it.