Therm-A-Rest hiking mattress. Most sporting goods stores have them plus Cabela's on-line. They are self inflating and very light for backpacking. We like the shorter ones (top of head to knees)to keep size and weight to minimum. Don't over inflate and keep covered with towel - the sun will heat and overinflate. Mine is approx. 10 yrs old used approx. 4wks a year on the beach and still doing well.