It is connected to Romani Plains by the Boneyard Bridge and Rauru Settlement Ruins by the Helmhead Bridge. The surviving ruins of Hyrule Forest Park are located here. A century after the Great Calamity, East Hyrule Castle is a dangerous place as two Guardian Stalkers patrol here night and day while a Stalnox reanimates in the southeastern forest at night. Despite these dangers, three Koroks can be found hiding on the island. A Treasure Chest containing a Phrenic Bow can be found in a small cave covered by Weak Walls. The cave also makes a great place to create a Campfire as it shelters it from the rain. The Stalnox has a Flamespear, Giant Boomerang, and Royal Broadsword stuck in its body allowing Link to acquire them by defeating it though he should eliminate the Guardian Stalker east of the forest to avoid confronting both and maybe even the Guardian Stalker that patrols on the island's northeast section just to be safe as either could be alerted by battling the Stalnox. During the day a Stalnox skeleton can be found in the forest as it only reanimates at night. Though the island is accessible to Horses and even has a road they will follow Link must becareful as the island's dangers can easily kill them though the Guardian Stalkers are a far more dangerous threat to them and Link than the Stalnox.
It can be seen as the eastern counterpart of Hyrule Castle West a large island located west of the Castle where the ruins of Castle Town Prison is located. Both islands are named based on the mini-bosses located on them as East Hyrule Castle is listed above the Stalnox's boss health meter as neither location is named on the Sheikah Slate's map. Despite its name it is not part of the Hyrule Castle dungeon map and is located outside the castle itself.