Like Hyrule Castle Town Ruins and Hyrule Forest Park, Hyrule Castle West is not part of Hyrule Castle as it lies outside the Hyrule Castle dungeon map. The island was once home to Castle Town Prison before it was destroyed during the Great Calamity. It is connected to Hyrule Castle Town by the Moat Bridge. The Noya Neha Shrine is hidden within a cave within the mountain in the southwest portion of the island. A Guardian Stalker and Guardian Skywatcher patrol the area near the prison ruins. On the mountain near the prison ruins is a Stone Talus (Rare). The name Hyrule Castle West comes from this Stone Talus as the location name appears above its name and boss health bar. The Sheikah Slate map only features the name of the prison and the location of the Shrine once it is discovered.
It can be seen as the Western counterpart of East Hyrule Castle the island where Hyrule Forest Park is located and gets its name from the Stalnox found there as East Hyrule Castle is listed above its name and boss health bar with only the name of the park being listed on the map once it is discoverd. Both locations are also found outside the Hyrule Castle dungeon map despite their respective names implying the opposite. Both islands also have several Koroks found hiding on them despite the presence of dangerous Guardians and mini-bosses found on each island.