What is the name of the sunken Expansion Pass area in Pokémon Pokopia?

Bubbly Basin is the sunken Expansion Pass area in Pokémon Pokopia.

Bubbly Basin is the first area introduced through the game's paid Expansion Pass. It is a submerged version of Cerulean City, pushed beneath the ocean by rising sea levels. Accessing the area requires Ditto to use Dive, allowing exploration of underwater trenches and other seafloor locations.

The area adds aquatic-themed Pokémon and furniture. Its main construction project is an underwater sea temple, which Ditto undertakes after receiving a request from the Popplio who introduces the town.

Bubbly Basin was released as the first Expansion Pass part on August 5, 2026. It should not be confused with Bleak Beach, which is a base-game area containing a devastated version of Vermilion City.