This Achievement is obtained using the well within the Geothermal Valley, from the Base Camp you first encounter proceed into the village where you will see a well, behind the well is a small building/shack which can be accessed using the small crates to the front left of the building. Hop up onto the box and then jump up onto the ledge and make your way over to the left side of the awning, this is where you will jump from.
If you struggle to reach the top of the small building use the extended grapple to pull yourself up.
Back up as far as you can get and click the
to run, as you hit the edge hit
to jump and then quickly tap
to perform a swan dive into the well below.
This might take a few attempts and timing is crucial but it is definitely achievable.
Thanks to DeltaPhoenix08 for showing me where and how to get the Achievement.
The below video shows how to get the Achievement.