The Story of the Blue World - S1.E12

The Open Diver course begins, with Futaba and Hikari paired up as buddies. Futaba loses one of her fins on the way to the descent point, but it gets picked up by another diver, turning her fears of the unknown world beneath her into excitement. Guided by the bubbles of the other divers, Futaba reaches the bottom of the ocean floor, wowed by the scenery and sealife spread out before her. Clearing all the tasks before her, Futaba passes the course with flying colors and becomes a fully-fledged Open Diver. Afterwards, Futaba and Hikari thank each other for everything that's happened since they became friends.