Seaside Cave

14 Pokémon can be caught at Seaside Cave in Unova — highlighted on the map below.

Sitting between Undella Bay and Route 21, the Seaside Cave is the first area in its game to demand an HM, since Surf is needed to approach it from either side. Although reachable immediately upon arriving in Undella Town, Black Belt Rocky turns explorers away until Team Plasma has been driven out of Opelucid City. The two-floor cavern has three exits — one to Undella Bay, one to Route 21, and one to an isolated section of that route where the Plasma Frigate waits — plus a Strength puzzle on its lower level.