Body temperatures during three long-distance polar swims in water of 0–3 °C

1.We report body temperature responses in a single individual to 3 swims of 1000 m or longer in ice-cold water (0–3 °C) during which he swam the normal crawl stroke with his face in the water whilst wearing only a swimming costume, swimming cap and goggles.2.He began each swim with a rectal temperature between 37.8 and 38.4 °C, which he maintained above 37.5 °C for more than 20 min. Following a swim of 1.6 km in water of 2–3 °C his lower limb muscle temperature fell to below 32 °C.3.There was a marked post-swim after-drop in his rectal temperature reaching 33.6 °C 13 min after the 1.6 km swim in water of 2–3 °C.4.Re-warming in a hot shower usually returned his core temperature to 37 °C within 70–90 min after the swims. Re-warming for 70 min after the 1.6 km swim failed to increase his lower limb muscle temperature.5.This study may have identified the limiting durations for swimming at 0–3 °C without protective clothing in this specific individual following an intensive programme of acclimatized to such cold water.