Darkwater Pass

You can find it by traveling from Windhelm to Fort Amol, and from there follow the path southward to Darkwater Crossing. The entrance can be found next to a waterfall roughly southwest of the Crossing.

A chest is located behind the small waterfall adjacent to the main entrance. The cave is inhabited by Falmer and Chaurus. On the way to the large waterfall, there is a silver ore outcropping on a side bank of the stream.

Under the large waterfall inside the cavern there is a Falmer chest that holds leveled loot.

To find the lever to meet Derkeethus, stand on the cage above his cell and turn North-East, in a small crevice in the North-Eastern wall you'll see the lever that lowers the door to allow access to him. A torch will help light up the cave. Having helped Derkeethus, he is a possible partner and follower. He normally lives at Darkwater Crossing.

A skeleton with loot is near the exit, in the bottom of the river.