The Old Sea Map is an item that was only officially released in Japan during an event called the Pokemon Festa. Like many other Pokemon items, this item was never released internationally. The only way to access it in non-Japanese versions of “Pokemon Emerald” is to use a cheating device, such as Action Replay.
The Old Sea Map is used in “Pokemon Emerald” to access Faraway Island, which is the island that Mew inhabits. To gain access to the island, the player needs to take the Old Sea Map to the S.S. Tidal, located in Lilycove City. After reaching the island, players are forced to play a game of hide and seek with Mew before they are able to engage it in a battle.
To obtain this item in other versions of “Pokemon Emerald,” the player needs to use the Action Replay that was designed to work with the GameBoy Advance. The code needed to access the item is 5b1cb4d7 10fa9do5. Players should exercise caution after getting the Old Sea Map by using the Action Replay. Since the map is not supposed to be obtainable in these versions of the game, glitches are known to occur, including the corruption of saved data.