The Cold Half is a 15 km extreme winter marathon swim in Hong Kong Island in February by Open Water Asia. The Cold Half (or the Cold Half & Cold Standard Extreme Marathon Swim) is modeled after Asia's most popular marathon swim, the Clean Half, except the water temperature is more to the liking of marathon swimmers, channel swimmers and adventurists of various types than the water temperatures during the Hong Kong summer. The expected water temperature is 20-21ºC (68-69.8ºF) with an expected air temperature that can range from 12.7-22ºC (55-72ºF). The swimmers will also encounter The Wall, a body surfing section in the middle of the course. It is one of Asia's Top 50 Open Water Swims and part of the Cold Standard.