Thames Path 100

How flat is the TP100 course and why is that significant?

The Thames Path 100 is exceptionally flat by every measured metric. It ranks 4th flattest out of approximately 390 trail races in the DiscoverTrailRaces database by proportion of flat terrain, and 5th-lowest for elevation gain per kilometre at roughly 11.8 m/km. The average uphill gradient across all climbing sections is around 3.95 percent — the 8th gentlest in the database — and the average descent gradient ranks 7th gentlest of all measured courses (inverted scale where rank 1 equals most gentle). This makes the TP100 significant in two ways: it is genuinely accessible for runners who struggle with technical mountain terrain, and it creates a unique mental challenge — 161 kilometres of flat, featureless riverside running tests pacing discipline and mental resilience far more than gradient management.

How much does it cost to enter the Thames Path 100 and how hard is it to get in?

Entry costs £220 for affiliated runners (£222 unaffiliated). The 2026 edition was sold out and running on a waitlist, with 300 places available. Entries typically open by ballot and fill very quickly. A qualifying race is required: runners must have completed a 50-mile event within 15 hours between 1 January 2020 and race day. The race is part of Centurion Running's Grand Slam of four 100-mile races; Grand Slam entries open alongside individual race entries. The 2026 date was 2 May; 2027 entry details are expected to be announced later in 2026.

Is the Thames Path 100 a WSER qualifier and what does that mean?

Yes. The Thames Path 100 is a qualifying race for the Western States Endurance Run (WSER), the most prestigious 100-mile trail race in the world, held annually in California. To use the TP100 as a WSER qualifier, runners must finish the race within the cut-off time (30 hours) in the year of their WSER application. Runners still enter the WSER lottery separately — completing a qualifier gives one lottery ticket, with additional tickets for each subsequent year of unsuccessful applications. The TP100 also has UTMB Running Stones (7.02 stones awarded on completion). WSER qualification applies to finishers of the full 161km distance only.