The Dudley No. 1 Canal (there's also a No. 2) runs for five miles between Tipton and the Stourbridge Canal at the bottom of Delph Locks. Much of this is the famously claustrophobic Dudley Tunnel, where boats are legged through by manpower alone. The canal formerly served the Round Oak steel works, now transformed into the Merry Hill shopping complex.

Dudley Tunnel passes directly underneath the town and its castle, through a remarkable network of limestone caverns. The tunnel is navigable, but size restrictions and a one-way system apply. Boaters should apply for details from Dudley Canal Trust on 01384 236275.

But if you don't have your own boat, you can still explore the tunnel complex. The Canal Trust runs regular in-and-out boat trips into the caverns, and through the summer months, there are trips all the way through the tunnel - one of Britain's longest. "