Surrounded Sea (Japanese: とざされたうみ Closed Sea) is a dungeon in Pokémon Mystery Dungeon: Explorers of Time and Explorers of Darkness and Pokémon Mystery Dungeon: Explorers of Sky. It is unlocked after Sunflora mentions finding treasure there. It has 20 floors and the last floor houses a Warp Point to transport the player out of the dungeon and a Wonder Egg that will hatch into Manaphy, as well as three Deluxe Boxes which contain Reviver Seeds. In subsequent visits, after clearing the dungeon the team can proceed to Miracle Sea to continue exploring.
After the player completes the main storyline, Lugia can be found on the 18th floor if the player has obtained the Mystery Part or Secret Slab and it is in the Treasure Bag.