Although this is not a cycle path this should be monitored. MCC, Fire and Police are proposing gating and 12 hour closures of this section of path. This is due to a number of fatalities by drowning.
This is a fairly interesting and somewhat unpleasant section known as the Undercroft.
I will scout the site to see if there is an argument for creating a cycle path to encourage more people to used this area with the proven argument that more people creates safer environments. I suspect this will not be practical but worth checking before a right of way is lost.

http://www.manchesterconfidential.co.uk/News/Rochdale-Canal-Towpath-To-Be-Gated#.U8TOROVtDHg.twitter