Nature sounds. See more here, courtesy of our friends at the PNW Chapter of the Audio Engineering Society and Dan Mortensen. Dugan calls it "immersive" and having enjoyed hiking and camping for decades, I'm inclined to agree. 
https://www.youtube.com/watch?v=f5Ya36u1_Vg
Dan is a man of many, deep talents and one helluva nice guy whom I have had the honor to meet on numerous occasions. During Covid when they couldn’t do their annual trip to Yosemite to document the sounds he and his crew camped a couple of nights at our Sierra Foothills place (oak/pine woodland at ~3000 ft) and apparently got quite the trove of animal sounds. It exceeded my expectations and while I could not identify some sounds I’m sure Dan et al. figured it out.
--Frank
