The End of an Undersea Childhood: A Lull in the Sea (Anime, 2013)

When their school closes, four life-long friends from the underwater village of Shioshishio--Hidari, Manaka, Chisaki and Kaname--attend junior high on the surface. There, they navigate adolescent rivalries, the costs of love, and the loss of childhood. An unabashed, tender, sometimes heartbreaking coming-of-age story. Episodes 1-6 make a good viewing arc.