Despite his attempts to distance himself from the group, Iori gets quickly swept up in their antics, while his cousins try to show him the wonders of diving into the ocean and sea.

[53] It aired for 12 episodes from July 14 to September 29, 2018, on the Animeism programming block on the JNN-affiliate station, including MBS, TBS, and BS-TBS, and on AT-X.

[54][a] The opening theme song is "Grand Blue", performed by Shōnan no Kaze, while the ending theme song is "Konpeki no al Fine" (紺碧のアル・フィーネ), performed by Izu no Kaze (a group formed by Yūma Uchida, Ryohei Kimura, Hiroki Yasumoto, and Katsuyuki Konishi).

[55] In September 2024, a second season was announced, with Takamatsu returning as director and scriptwriter and Liber joining Zero-G as animation studios.

[58] It was directed by Tsutomu Hanabusa, and originally scheduled to release on May 29, 2020;[4] however, it was postponed to August 7 of that same year, due to the COVID-19 pandemic.