In Dark Souls, what is the name of the key that opens the door to the Depths?

In Dark Souls, Key to Depths is the key that opens the door to the Depths.

The player receives the key after defeating the Capra Demon in Lower Undead Burg. It opens the large locked door near the lower burg route, leading into the Depths. This area contains narrow passageways, rats, butchers, and the route toward the entrance to Blighttown.

The Key to Depths is distinct from the Basement Key. The Basement Key opens the first route from the Undead Parish toward Lower Undead Burg, while the Key to Depths continues the progression from Lower Undead Burg into the sewer-like area below. The distinction matters because both keys are tied to early-game doors and are easy to confuse.

The Depths also contain the Large Ember, an important upgrade item, and the arena for the Gaping Dragon. The key therefore marks a major transition in the early Lordran route.