Arnika: Spaceport hanger closest to main building

Bayjin: (hidden) #5, 2 bottles. Another not hidden in a cell by Glumph and Jan-ette in the hut at #1.

Bayjin Shallows: #5 Near the exit/entrance to Bayjin

Mt. Gigas Caves: Near Underground Lake: next to the chest at the end of the passage accessed by either falling in the northernmost hole and going right down the passage or traveling west across the lake up a  passage and hanging a left just before the hole above. 

Mt. Gigas Peak: Upon first entering there is a crate (#2) that can be opened containing this item.

Old Mine Tunnels: Hut just north of RFS-81's initial location

Rapax Cellar: Room behind the Jailer and the cell that opens to the secret passage (#3).

Swamp: Right near the Tar Pit #3

Trynton Upper: Observatory #9 Next to Madras and his telescope. Another in the room just before encountering the Giant Spiders at #5

Umpani Base Camp: Behind (east) the Roadhouse #2 & Commissary #3 inside the walls