In 1.4 something was changed about how resting and oxygen works, you used to be able to pseudo-autoexplore until you were lowish on air (~50%?) but now that's not the case anymore, most of the time your character just rests until they're low on air and this made underwater even more annoying without waterbreathing, would be nice if it went back to how it used to be.
totallynotyeekbias
"As dying is one of the leading causes of death, you should avoid dying." -rekenner
"I'll bond with a cactus until my buttcheeks touch the sand before I play nethack again" -Gagarin