Two Tunnels Ultra 50k

The Two Tunnels 50km is run entirely on the "Return Ticket" route, an out-and-back course starting and finishing at Brickfields Park in Bath and completed as five laps of the officially measured 10km course. Runners head out along the Kennet & Avon Canal towpath before passing through both the 408 metre Devonshire Tunnel and the 1,672 metre Combe Down Tunnel, the longest underground running section of any UK race distance. The course is almost entirely tarmac, aside from a small stretch of grass at the start and finish, and is flat throughout, avoiding the city centre and hillier sections used by the marathon and half marathon. With nine feast stations along the way offering food, water and electrolyte drinks, and an 8.5 hour cut-off, it's a genuinely accessible way into ultra distance running, run largely underground and along calm, scenic waterside paths.