Blisworth Tunnel has no tow path inside, but is wide enough for two narrowboats to pass in opposite directions. Work began in 1793, but errors by contractor left a wiggle in the tunnel, and after three years work it collapsed due to quicksand, claiming the lives of 14 men. It was then decided to begin again with a new tunnel. By the time the rest of the Grand Junction Canal had opened between London and Braunston, Northamptonshire in 1800, apart from the crossing of the River Great Ouse, the section of canal from Blisworth to the lower end of Stoke Bruerne locks
Sapperton Canal Tunnel short section to create a passing basin. Sapperton Tunnel was passable until at least 1966 but is now blocked by roof collapses over several hundred yards, mainly in sections where the ground is fuller's earth. Restoration is proposed by the Cotswold Canals Trust as part of their project to re-open the canal route from Thames to Severn. The trust operates tourist boat trips into the tunnel in winter months. The Sapperton railway tunnel, on the Golden Valley Line, follows a broadly similar route under the 'Cotswold Edge'. There have been proposals for a national network of canals and aqueducts to