Dunbarrow Cove is a cave located behind and under Castle Anvil. The first section of the cove is called Smuggler's Cave and contains some crates, chests and barrels and can be accessed in the vanilla game. However, the lower passage leads to Dunbarrow Cove itself, which is only available with The Thieves Den plug-in, while the upper passage, which can only be opened with the Smuggler's Key, leads to a secret section of Castle Anvil and ends up in the Umbranox private bedchambers.