From Yen Press:
College student Tsuneo loves the ocean and the creatures it harbors, and he dreams of studying abroad in faraway waters. All he needs is enough funds to go, so when a girl in a wheelchair suddenly barrels into his life, he readily agrees to work part-time as her caretaker. Getting close to the prickly Josee is easier said than done, but before he can give up, an impromptu trip to the beach shows them both that sometimes, they must take that first plunge to see the wonders that await.

Based on the anime movie and not the original short story.