Thames Ring 250 Mile Ultra Marathon

Thames Ring 250 Mile Ultramarathon

Don't let the lack of mountains fool you. The Thames Ring 250 is one of the most gruelling and iconic ultra marathons in the UK. Spanning a colossal 250 miles (measuring closer to 256), this is a true test of physical stamina and mental fortitude.

Organised by Challenge Running, the Thames Ring 250 ultra holds a special place in British ultramarathon history as the first race of its distance in the country and, for many years, the longest non-stop trail race in Europe. It follows an epic anti-clockwise loop starting in Streatley-on-Thames, tracking east along the River Thames, heading north up the Grand Union Canal, and sweeping back down the Oxford Canal to return to the start line.

While the route is almost entirely flat, featuring riverside paths and rural canal towpaths, the immense distance, sleep deprivation, and relentless pavement pounding make it an exceptionally demanding prospect.

Course

The race starts and finishes at the Morrell Rooms in Streatley-on-Thames. You will navigate using provided maps and GPX files through a mix of tranquil rural waterways and some urban stretches.

Runners are supported by checkpoints spaced roughly every 25 miles. These checkpoints are absolute lifesavers, offering basic hot and cold foods, hydration, and, crucially, sleeping tents (available after the 75 mile mark).

To maintain the raw challenge of the Thames Ring, the rules are famously strict:

• No Outside Support: Friends and family can only assist you at the designated checkpoints. If supporters are caught bringing you food, drink, or gear out on the trail, you risk immediate disqualification. You must be entirely self-sufficient between CPs.
• No Pacers: Buddy runners and pacers are strictly forbidden. You are in this alone!
• Drop Bags: You are permitted one 20kg drop bag, which the event team will transport to each checkpoint for you. (Overseas runners get an additional travel bag taken straight to the finish).

Ready to take on the Thames Ring 250 ultra marathon?

The Thames Ring strips away the glamour of mountain running and replaces it with a relentless, flat grind that requires unparalleled mental resilience. With generous early-bird entry discounts, live GPS tracking included, and a massive, heavy finishers' medal waiting at the end, it is the ultimate bucket-list event for experienced ultrarunners looking to see exactly what they are made of. For full race info and registration details, please visit the official race website.