From Bulbapedia, the community-driven Pokémon encyclopedia.
Red Rock Isle (Japanese: 赤岩島 Sekigan Isle) is one of many small islands in the Whirl Islands archipelago. The Whirl Cup is held here, in Scarlet City.
In the anime
Ash and his friends arrived on Red Rock Isle at the end of Mantine Overboard!, when they were taken there by Luka.
It was the setting for the anime episodes from Octillery The Outcast to Plant It Now... Diglett Later.
The events of Octillery The Outcast, Dueling Heroes, and The Perfect Match! follow the annual Whirl Cup competition.
In, Plant It Now... Diglett Later Ash and his friends visited Diglett Village. During the episode, they tried to protect the older residents of the town from a group of thieves who are attempting to steal the town's Diglett upon which the local economy is based, only to find out the thieves were the children of the older residents and were trying to help their parents.
Cities and towns