Geothermal Valley - High Dive Challenge

Any time after obtaining the OIL FLASK and lighting the signal fire, return to the zip line where you first crossed over to the spire. See the flammable barrier in the archway at the front of the spire? That's where we're headed. Zip down to the base of the spire and make your way up and around the back of it, just like you did earlier. (Check these screenshots if you need a refresher.)

When you come to the first ledge on the north side of the spire, look down and you'll see your zip line and a red, wooden ledge. Drop down here.

Step out onto the red ledge, turn around...

...and use a fire arrow to burn down the barrier.

Get the pistol and rifle ammo inside.

Then step out onto the red diving board. To do a swan dive, stand at the edge and simultaneously press Forward and Jump, then a split second after takeoff press LT/Right Mouse to go into a dive.

Like so.

This initiates the High-Dive Challenge.

NOTE: If you're having trouble with the swan dive, it may help to point the camera downward as you dive and/or to press Dodge (C) instead of the Right Mouse button if you're playing with keyboard and mouse. Both worked for me, but you may have better luck with one or the other. You can complete two more high dives now if you like. The fourth cannot be accomplished until later in the game, when you are able access the northwest corner of the level. To save backtracking, you could also wait and do the dives later when you revisit this level for other reasons. I will include reminders later in the walkthrough.

After diving off the spire, swim to the northwest, climb out on the stone ledge at water level, and use the tree to climb onto the ledge above. The the second diving board is in the guard tower near the Remnant hunter's cabin. (It's circled in the screenshot above.) Of course, you can also approach it from the other side.

Once you have completed the Defensive Strategy Mission, the guard tower by the lake, near the Remnant hunter's cabin, is fitted with a ladder.

Climb to the top and swan dive off the red diving board (2/4) to tick off another high dive for this challenge.

The next diving board (3/4) is near the entrance to the Pit of Judgment Challenge Tomb. To get there, start near the Ruins Encampment Base Camp, where Sofia was giving her pep talk earlier, and follow the path to the north, behind the falls.

Dive off the board into the pool as shown here.

The final diving board (4/4) is located near the top of the waterfall, above The Architect's Crypt. It is not accessible until later in the game, after you've completed the FLOODED ARCHIVES level and re-enter the Geothermal Valley in the northwest corner near the Ridgeline Base Camp. This screenshot shows the diving board from below.

Here is the fourth diving board seen from the Ridgeline camp.

Recapping the swan dive maneuver: stand at the edge of the board—or run toward the edge if that works better for you—and simultaneously press Forward and Jump, then a split second after takeoff press LT/Right Mouse to go into a dive. (Check the note above if you're having trouble making it work with the standard controls.)

If it doesn't work the first time, press the Menu/Start button on the Xbox controller or Esc on the keyboard and reload the last checkpoint. Then you can try again without having to run all the way back up the hill.

When you complete the fourth high dive, you'll receive XP and 2,000 Expedition Credits.