The River Hyndburn drops into a culvert that takes it around 300m under a field
This culvert takes the Woodnook Water under Accrington town centre where it meets with the Warmden Brook.
Warden Grotto is around 700m long and takes the Warmden Brook under South East Accrington before it joins with Woodnook Water
This small culvert carries the Swinnel Brook for around 120m on the northern side of Haslingden
The River Irk travels under Middleton town centre for around 500m in a couple of parallel concrete box culverts.
The River Calder flows through Cornholme in a few stone culverts, we had a look at the first one which was around 650m in length.