The Extraordinary Tunnel That Was Shut to Protect a Colony of Bats

Hidden beneath the hills of the Wye Valley lies one of the most unusual and atmospheric walkways in Wales — a 1,080‑metre tunnel so mesmerising that stepping inside feels like entering another world. But this extraordinary place isn’t just a scenic route for walkers and cyclists. It is also home to some very special residents.

The Tidenham Tunnel, which links Tintern and Sedbury along the Wye Valley Greenway, is a vital habitat for lesser horseshoe bats. Around 26% of the entire UK population of this rare species lives in the surrounding area, making the tunnel one of the most important bat roosts in the country.

Because of this, the tunnel is closed every winter to protect the bats during their hibernation period. Even when it reopens for the summer months, the lighting is kept deliberately low to avoid disturbing them. Visitors are asked not to use torches or flash photography, and not to look for bats as they pass through.

A historic railway reborn

The tunnel first opened in 1876 as part of the Wye Valley railway line. After decades of disuse, it was restored in 2019 thanks to volunteers and local charities, before reopening to the public in 2021. Today, it forms part of the five‑mile Wye Valley Greenway — a flat, scenic route that has become a favourite for families, cyclists and walkers.

Inside, the tunnel’s high arches and soft, dim lighting create a hypnotic atmosphere. The bats roost in alcoves that run the entire length of the structure, and their presence is the reason the tunnel feels so dark and peaceful.

Jeremy Cowen, volunteer coordinator for the Wye Valley Greenway, said around 50 bats currently live in the tunnel. They are protected by law, meaning any deliberate disturbance of the bats or their habitat is a criminal offence.

A route designed around nature

The tunnel is free to enter and open daily until 8pm throughout the summer season. It will remain accessible until October 1, 2026, when it will close again for the bats’ winter hibernation.

Visitors are advised to keep left to avoid collisions with cyclists, and on bright days, the Greenway team even recommends wearing sunglasses for the final half‑mile before entering the tunnel so your eyes can adjust to the darkness.

Kevin Ford, destination manager for Monmouthshire, said the Greenway has become a hugely popular route:  

“It’s the best way to cycle between Tintern and Sedbury because it’s completely flat,” he said. He added that those passing at dawn or dusk may be lucky enough to see bats entering or leaving the tunnel.

A rare blend of wildlife, history and adventure

The Tidenham Tunnel is more than just a walkway — it’s a remarkable example of how historic structures can be brought back to life while protecting the wildlife that depends on them. Its reopening each summer offers a unique chance to experience a piece of railway history, a thriving bat habitat and one of the most atmospheric tunnels in Wales.

More information and opening times can be found on the Wye Valley Greenway website.