Skull Keep is a fortress in Blood Bath Bay, which served as the headquarters, main base of operations, and residence of Captain LeFwee and his crew. Several pirates can be seen on the roof walking around or sleeping.
Its outer structure is simply a large stone skull. There are two wooden walkways that connect to it. On one side of the fort are several objects in the water that allow access to the back, where there are more walkways that lead up to the roof.
After stealing the treasure map, LeFwee stashed it in the Skull Keep. Later on, he and his men raised the bridges to the fort when they encountered Penelope's Hover-Spectrometer. Bentley and Penelope infiltrated Skull Keep in order to retrieve the hidden treasure map that will lead the Cooper Gang to Dagger Island in search of Reme Lousteau's stolen diving gear.
During the gang's heist, LeFwee stated he kept Penelope prisoner inside Skull Keep, although in actuality, it was a bomb disguised as Penelope used in an attempt to eliminate Sly Cooper. LeFwee hid the real Penelope inside the lower deck of his ship, the Death Hen. Once LeFwee was defeated and killed, the Skull Keep was abandoned.
- Black Spot Pete referred to the fort as "Yonder Keep."
- On the roof is a cannonball punctured right into the surface.