The video shows a close-up of a nudibranch, a type of sea slug, swimming in the ocean. The nudibranch has a vibrant and colorful body with patterns of pink, black, and white. It has two long, thin tentacles that it uses to navigate through the water. The background consists of blurred coral reefs, indicating that the nudibranch is in its natural habitat. The video captures the nudibranch's slow and graceful movements as it explores its surroundings.