Gulper lagoon is a river, flowing downhill and ending in a small pond of still water. There are large trees over the river, with up to four gulpers dangling from their branches. The lagoon is littered with human bones.
A shack with a tinker's workbench is at the bottom of the nearby cavern. Strangler vines have grown to create a ramp to easily climb down to it.
Gulper lagoon appears only in Fallout 76.