After you have found the Old Sea Map on Route 22, take it to the old captain in Sunset City. He can take you to this remote island.

Hidden in the grass is the extremely coveted Mythical Pokémon: Mew.

 Obtainable Pokémon Edit

Pokemon Level Location
Mew 30 Hiding in the grass.

Obtainable Items Edit

Items Location
Comet Shard Item Ball near the entrance.

Trivia Edit

The Old Sea Map was initially intended to be a limited time Mystery Gift, but due to technical issues, was made into a regularly obtainable item.