Sognsvann (or Sognsvannet) is a 3.3 km circumference lake just north of Oslo, Norway. Lying just within the greenbelt around Oslo, the lake is a popular recreational area, used as a camping, picnicking and bathing destination for the residents of Oslo during the summer, as well as a cross-country skiing, skating and ice fishing destination in the winter. The trail around it is used for walking or jogging all year. Every year in August, swimming and running take part in Sognsvann as part of the Oslo Triathlon. Cycling around the lake is prohibited due to large number of people covering this road on foot. Disabled access is good to and around the lake. Part of the lake's popularity stems from its easy access from Oslo; Sognsvann station, located on the south end of the lake, is the final stop on line 5 on the Oslo Metro. Svartkulp ("The black pool"), a small forest lake which is one of three nudist beaches in Oslo, lies a few hundred meters to the east of Sognsvann. The geographical center of Oslo municipality and county lies in the middle of this pool.