Prepper Stash: The Angel's Grave
This stash is in the depths of Horned Serpent Cave, in Faith's Territory. You'll need the grapple to complete it.
The start note is on some long crates in front of the cave's gated entrance, on the north side of the hill.
Grapple up to the clifftop above.
There will be a small number of hostiles up top, but they're too focused on corpse detail to present much resistance.
When they're dead, drop down into the body pit.
On the east edge is a grapple point that will lower you even further into the cave.
Inside the cave proper, follow the trail of lanterns.
Essentially, you'll keep criss-crossing back and forth over than same body of water, first just by hopping from rock to rock, then a combination of rock-hopping and grappling.
After a final swing, and some ledge-mantling, a zip line will take you to the foot of some rough-hewn stairs.
Climb the stairs and duck through a low tunnel to find the final part the cave- the part with active resistance.
Still, it's just a man and his dog. Dispose of both, then claim the stash at the end of this path for completion.
The stairs left (north) will take you back to your starting point at the gate.