Note: Please only look at the maps below if you're experiencing trouble trying to find things! It's no fun spoiling where things are if you can find them yourself!
The Southern and Northern Slurries are big and confusing, and the Postman's maps can be a bit small, so I've marked where various things are below! I'm leaving out marking where other nests are because there's more of them around.
Green dots - cactii
Red dots - crocodile nests
Pink dots - cameras
Yellow line - entrance to the Abandoned Labs (opened by the Northern Slurries engine)
Northern Slurries map
Southern Slurries map