This is some beautiful animation. I like how Ariel's hair flows. And the music really complements the tone. The transition in the lighting was very smooth I didn't even notice it.
That being said the sea's movements look awkward. The sea and the clouds really juxtapose one another. However both of them and and the lines of the sea also eventually took my attention away from Ariel and Flounder because it shone so bright.
But great work regardless!