My last two items in Geothermal Valley are two survival caches. I suspect that I missed one of those maps/backpacks that reveals their locations because everything else is marked as found in the Region Summary.
You likely missed caches near the Infirmary base camp & tomb (north part of the map) so fast travel there. Go to the puzzle area and swim to the right, where you can dive underwater and enter another area with a cache and a backpack (satchel) that will reveal any others in the area.
There are two caches in the infermary area,one near the steps leading to the swing bars,the other is just before the camp save to the side of a small piller near archway entrance on the right.That gives me one left to find ,i am on 99% in the game and cant find the last cache,the two in the infermary where not on the map.If you look through the grill window near the steps of cache find and press the find button you can see the out line of a satchel ,how to get there though .
In the infirmary you can go under water just past the stairs to the swinging bars and there's a backpack and the last survival pack.