The Tunnel Marathon - Portsmouth

NOV

21

2026

An underground marathon at UCAP BUNKER near Portsmouth on 21 November 2026. The multi lapped route runs through low tunnels, has a six and a half hour cut off, and requires a headtorch and cycle helmet.

Sat 21 Nov 2026

Portsmouth,

Website Registration

26 miles

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The Tunnel Marathon Take 3 2026

The Tunnel Marathon Take 3 2026 is described as the UK’s only fully underground marathon. It is scheduled for 21st November 2026 and will take place at UCAP BUNKER, located about two miles north of Portsmouth at postcode PO17 6AR. The venue sits roughly 100 ft underground in the former U.G.H.Q used by the Royal Navy during the Normandy invasion and is also used for Airsoft close quarter battle training.

Entries open on 6th March. The event has a race cut off of six and a half hours. A headtorch and a cycle helmet are mandatory for all participants.

The course will be a multi lapped route similar to other underground or museum style marathons. The exact final route is not yet finalised. The route will use several tunnels, some with a height of about 6 ft, which will require stooping in those sections. These low tunnel sections are around 20 m long and will be encountered frequently because of the lap format. Visit the organization's website for the most recent information.

26 mi

Marathon