Cinnabar Island

23 Pokémon can be caught at Cinnabar Island in Kanto — highlighted on the map below.

Cinnabar Island rises off Kanto's southern coast below Pallet Town, dominated by a large volcano. Route 21 links it north to Pallet Town while Route 20 runs east toward the Seafoam Islands. Journals in the abandoned Pokémon Mansion reveal Mewtwo was created there, and the island's lab can revive Pokémon from Fossils. A volcanic eruption devastated the island a year before the Johto-era games, forcing Gym Leader Blaine to relocate his Fire-type Gym to the Seafoam Islands.