Les Grands Bains du Monetier is the valley's thermal-bath stop, with indoor and outdoor pools, jets, steam rooms, and hot water that feels especially good after a cold ski day. The setting matters as much as the facilities: you soak at the upper end of the valley with mountains rising above the village.
Book ahead in busy weeks. It is popular with families, couples, and tired skiers, so the quietest sessions are usually away from school-holiday peaks.