Thames Ring 250 Mile Race 2027

The Thames Ring 250 begins and ends in Streatley-on-Thames, taking runners on a 250-mile anti-clockwise circuit. Held biennially, the race has a 100-hour time limit, requiring participants to complete the distance within four days and four hours. The course primarily follows canal towpaths and riverside trails, offering relatively flat terrain. However, the sheer distance, navigation challenges, and sleep deprivation make it significantly more demanding than its profile indicates. The route proceeds east along the Thames, transitions to the Grand Union Canal, and then circles back towards the Thames via the Oxford Canal before concluding in Streatley. Runners navigate using maps and GPX files, as the course is not fully marked, with checkpoints positioned approximately every 25 miles. This event was the inaugural UK race of its length and, for an extended period, the longest non-stop race in Europe. With an average completion rate of only about 41%, and recent editions seeing even fewer finishers, the participant field largely consists of seasoned ultra runners capable of managing nighttime running, extended solo efforts, and minimal sleep.