Winter Swimming, Krasnoyarsk, Siberia

Ice swimming is swimming in a body of water with a frozen crust of ice, which requires either breaking the ice or entering where a spring keeps the water from freezing over. This may also be simulated by a pool of water at 0 °C, the temperature at which water freezes.
Winter swimming is swimming in a body of water during winter. This may or may not involve freezing water, depending on the geographical location and the local temperature.
Ice swimmers typically dip their heads below the surface to ensure that they are completely wet, whether or not the water is over their heads. They usually do not swim beneath the ice, as it is easy to get disoriented when turning around and not be able to find one's way back to the hole. Some ice swimmers avoid this problem by swimming from one hole to another, or by swimming under the ice while tethered to the shore. Due to the diving reflex, a swimmer is able to hold his or her breath for a long time while under the ice.