sporting activities during the winter season including distance ice skating. Ice trails are created by natural bodies of water such as rivers, which freeze during winter, though some trails are created by removing snow to create skating lanes on large frozen lakes for ice skaters. Ice trails are usually used for pleasure skating, though the sport and recreational activity of Tour skating can involve ice skaters passing over ice trails and open areas created by frozen lakes. To date, speed skating and ice cross downhill are the only winter activities or sports whereby ice skaters use tracks and lanes designed to include bends rather than using a simple straightway. Some ice rinks are constructed in a manner allowing for a speed skating rink to be created around its outside perimeter. Tracks Speed skating track Speed skating tracks or "rinks" can either be created naturally or artificially and are made either outdoors or inside indoor facilities. Tracks may be created by having the lanes surround the exterior of an ice rink. The sport requires the use of a special type of racing skate, the speed skating ice skate. In speed skating, for short track, the official Olympic rink size is , with an oval ice track of in circumference. In long track speed skating the oval ice track is usually in circumference. Ice skating marathon tracks An ice skating marathon is a long distance speed skating race which may be held on natural ice on canals and bodies of water such as lakes and rivers. Marathon is a discipline of speed skating, which is founded in the Netherlands. The races concern speed skating by at least five skaters who start all together on an ice rink with a minimum length of 333.33 meters or on a track: Minimum distance longer than 6.4 kilometers and up to 200 kilometers for skaters who have reached the age of 17 prior to the skating season on July 1. Minimum distance longer than 4 kilometers and up to 20 kilometers for skaters who have reached the age of or the age of 13, but have not yet reached the age of 17 before July 1 preceding the skating season. Minimum distance of 2 kilometers and up to 10 kilometers for skaters who have not yet reached the age of 13 before July 1 preceding the skating season. Dutch skating tracks The Netherlands is home of