I finally found the leaky spot on my sleeping pad after 3 trips and a whole weekend of bad sleep
Kept waking up flat on the ground at Seneca Rocks and blamed my pad until I filled the tub at home and saw bubbles coming out of the valve stem, not the pad body. Took me about 15 minutes to spot once I actually submerged it, but I spent two trips re-inflating every 2 hours like an idiot. Anyone else had a valve leak that only shows up under water?
Did you check the valve with the pad fully inflated or did you dunk it while it was flat? I ask because those little spring valves can seal up fine when there's no pressure behind them, so they look good in the tub but leak once you're laying on the thing. Next time try filling it, capping it, and submerging the whole valve area while squeezing the pad to push air toward the stem. Also worth checking if the valve core itself is loose, since that's a two second fix with a core tool if the threads just backed out over time.