the transition between between water and land just shows a plane diving the screen ( not your fault I know ), but perhaps you can hide it with splash decal or by applying the wobble shader a little before?
About it being green lit - stranger things have happened, hell add in some child friendly elements where you have to collect X (random) beams with clear visual and auditory showing how many to collect and how many is left. ala "You have placed 2 of the 3 beams. you need 1 more beam"
The more I think of it the more I'm sure my son would love to play it - let me know if you need help with danish translations/voice