I built a backcountry hot tub once. We dug a hole next to a water source, lined the hole with our tent tarp, and dug a canal to bring in water. Then we heated rocks on a bonfire, poked them onto a travois made of tree limbs, and dumped them into the water. That actually worked pretty well, but the Nomad collapsible hot tub is a lot easier to set up.
This 225-gallon vinyl-sided pleasure vessel is 5 feet in diameter and 2 feet high (plenty of room for people who are already sharing tent space) and packs down into a 16-inch-square dry bag plus frame poles. It’s up and ready in no time.
You can figure out a clever hot water delivery system like we did, or bring the recommended Honda WX10 lightweight portable pump (sold separately) and fill the thing in 10 minutes from a handy stream or lake. The Nomad’s shiny heater coil unit quickly raises the water temp to something steamy, and that’s all there is to it. You’re soaking in the backcountry!