Frigid Water

Environmental Hazard

A creature can be immersed in frigid water for a number of minutes equal to its Constitution score before suffering any ill effects. Each additional minute spent in frigid water requires the creature to succeed on a DC 10 Constitution saving throw or gain 1 Exhaustion level. Creatures with Resistance or Immunity to Cold damage automatically succeed on the save, as do creatures that are naturally adapted to living in ice-cold water.

Source: Dungeon Master’s Guide (2024) p. 68