Pokemon Legends: Arceus - How to Surf Across Water

gamerant.com:

Since the Alola region, Pokemon has slowly moved away from Hidden Machines (HMs) and replaced them with a new feature called Ride Pokemon. At some point in each Pokemon game, players are given a Key Item that allows them to ride on Pokemon that can fly, surf, or move boulders. Pokemon Legends: Arceus doesn't have a Ride Pager or a Rotom Bike, but it does have the Celestial Flute. The flute functions the same as the Ride Pager in Sun/Moon & Ultra Sun/Ultra Moon, and the Ride Pokemon essentially serve as «HMs» in the overworld.

The first Ride Pokemon players will get in Pokemon Legends: Arceus is Wyrdeer. As more of the Hisui region is explored, it becomes obvious that trainers will eventually need a Pokemon that can cross water. Once trainers reach Cobalt Coastlands, they'll need to make progress in the story Mission and unlock Basculegion. Unlike Wyrdeer and Ursaluna, Basculegion can only be used in water.

Pokemon Legends: Arceus — How to Get Goomy, Hisuian Sliggoo, and Goodra Early

Basculegion is a new evolution of the new white-striped Basculin. While trainers can catch their own Basculin and evolve it into Basculegion, the Basculegion summoned by the Celestial Flute is the only one that can surf across the waters of Hisui.

In Mission 10: The Lordless Island, Kamado will send the player to Cobalt Coastlands to help Irida and the Pearl Clan. Upon arriving, players are challenged by Irida in another battle and are then directed to find someone named Palina. Follow the Mission 10 objective marker and speak to Palina and her Hisuian Growlithe. After this, she'll mention someone named Iscan. Once again, track down the objective marker and speak to Iscan. He lives in a Diamond Clan tent on Aipom Hill. Iscan will mention how he