This Mantine is a water-type Pokémon that appeared as a recurring character in the Where Are You Going, Eevee? mini-segments. It was soon made its proper debut in Pokémon the Series: Sun & Moon - Ultra Adventures Know Where You're Going, Eevee! as only a flashback from the said mini-segment, and physically in Alola, Alola!.
When a Wailord shaking the ship where a male Eevee with bushy hair, who is later nicknamed Sandy, was sleeping inside one of crates, which fell into the sea, causing him begin to panic and is about to drown after falling from the now sinking crate he was in, Mantine rescues Eevee and takes him to a safer destination. As it and Sandy are almost near the land, they had a little fun doing a stunt on the medium wave.
Finally, they found Melemele Island at Alola nearby, as Mantine drops Sandy there and bids each other farewell.
By the time after the Pokémon School starts a holiday, Mantine reunites with Sandy during the school's vacation. In afternoon, Mantine and the other Water-type Pokémon are somehow being kidnapped by Team Rocket’s Jessie and James, with Sandy arriving in time with his friend to save them.
None of Mantine's moves are known.