Ultra Deep Sea Nihilego .

By traversing the Ultra Wormhole via the Ultra Warp Ride, players can reach the Ultra Deep Sea,
where the Ultra Beast Nihilego resides.

The Ultra Deep Sea was formally known as Ultra Space in the Pokemon Sun & Moon games.
It's effectively the same map, and it also used the same internal ID for the location header.

The encounter itself has a chance of being shiny.
The details below refer to this specific file.

Species   Nihilego   Nickname   (default, in )   OT   PPorg   TID   171117   Distribution   In-Game Encounter   Location   Ultra Deep Sea   Dates   Nov 17, 2017   PID   Cannot Be Shiny   Games   US

Lv. 60

Nature   Calm   Ability   Beast Boost (1)   Item   None

Moves   (ITALIC means Relearnable)   Power Gem   Acid Spray   Stealth Rock   Mirror Coat

Format Ver.1.0.5-5, Post Updated Date:20171115_0249