Ultra Deep Sea, referred to as Ultra Space in Pokemon Sun and Moon, is one of the several worlds of Ultra Space accessible though Rarity 1 White Warp Holes after defeating Necrozma, it's the home of Nihilego. In Pokémon Sun and Moon, after Nebby evolves into Solgaleo or Lunala, it takes the player and Lillie to Ultra Deep Sea, where Lusamine is faced for the last time.
Ultra Deep Sea is a dark cave with a dark stone path that ends in a dead end with a small rock where the player can sit. There are many sparkling crystals surrounding the area, several Nihilego can be seen floating around.
Pokémon Sun and Moon
The player battles Lusamine after her fusion with a Nihilego. After the player defeats Lusamine, it's impossible to return to Ultra Deep Sea.
All her Pokémon have auras that boost their following stats by one stage:
- Special Defense (Clefable)
- Special Attack (Lilligant)
- Speed (Mismagius)
- Attack (Milotic)
- Defense (Bewear)
|Lv. 50||♀||Lv. 50||♀||Lv. 50||♀||Lv. 50||♀||Lv. 50||♀||Lv. ?||-|
|Ability: Magic Guard||Ability: Own Tempo||Ability: Levitate||Ability: Marvel Scale||Ability: Fluffy||Ability: Unknown|
|Item: None||Item: None||Item: None||Item: None||Item: None||Item: ?|
|Moonblast||Petal Dance||Shadow Ball||Hydro Pump||Baby-Doll Eyes||-|
|Cosmic Power||Teeter Dance||Mystical Fire||Safeguard||Hammer Arm||-|
|Metronome||Stun Spore||Power Gem||Flail||Take Down||-|
|Moonlight||Leech Seed||Pain Split||Recover||Pain Split||-|
Pokémon Ultra Sun and Ultra Moon
A Nihilego is found during each visit to Ultra Deep Sea. It has an aura what boosts its Special Defense by two stages.
| Held item:|
- In Pokémon Sun and Moon, the Rotom Pokédex doesn't work in the Ultra Deep Sea. In Pokémon Ultra Sun and Ultra Moon, Rotom always displays the Altar of the Sunne/Altar of the Moone minimap.
- All of Lusamine's Pokémon (except Bewear) have an angry expression instead of the normal expression.
- If a Pikachu, Cubone or Exeggcute evolves in Ultra Deep Sea in Pokémon Sun and Moon, it will still evolve into their Alola Form.