Key to the Seal

The Key to the Seal is a key in Dark Souls.

In-Game Description
Key to the floodgates of New Londo, which seal away the  Four Kings who fell to Dark. The Sealers flooded New Londo to banish the Darkwraiths and the Four Kings. The agonizing decision was made with the realization that countless lives, and the robust culture of the city, would be lost. The victims now roam the ruins as ghosts.