Ultra Crater (Japanese: ウルトラバレーUltra Valley) is the home of Celesteela, accessible commonly through Rarity 3 warp holes and rarely through Rarity 2 warp holes in Ultra Warp Ride, located more than several thousand light-years from Alola. It only appears in Pokémon Ultra Moon.
The Ultra Crater is actually a large expanse with several craters filled with a green substance. The land has what looks to be metal pipes growing as roots throughout the rock. A few red monoliths also stick out of the ground. Several geysers are also present shooting out steam. Several Celesteela are present in the ground and the world is frequented by earthquakes as Celesteela fly out of the ground and into the sky. A large mountainous expanse is pictured in the background. The sky is yellow possibly due to geothermal activity from the geysers.
A colored background means that the Pokémon can be found in this location in the specified game. A white background with a colored letter means that the Pokémon cannot be found here.
Celesteela absorb energy from the ground in this world, as hinted by their depiction in this world and their Ultra Sun Pokédex entry. They also glow and launch themselves into the sky, subsequently causing earthquakes, as shown in the first encounter with Celesteela in this world.