When I first started exploring the local railway environment as a young teenager by bike, the Leeds & Liverpool Canal towpath provided a nice traffic-free cycling route to get to various railway hotspots (Bamfurlong Jn, Standish Jn and the WCML just south of Wigan NW)
There were very few other cyclists or dog-walkers on canal towpaths in those days, and no cruising narrow boats, gaggles of ramblers or grumpy old men (or women) asserting their right of way - so a much less congested and more conflict-free environment than might occur today. In fact, I think back then cycling on the towpath was technically contrary to some British Waterways Board byelaw (there were rare 'No Cycling' signs at some entry points from roads) - but this regulation was universally ignored and never policed.
As a relative youngster, I was quite taken by the "simple but clever" principles used in canal construction and operation, especially around flights of locks, and the quality of the substantial late 18th/early 19th century masonry. I would linger around, taking in the details and figuring out how the various lock components, sluices and overflow channels worked, before cycling on to my rail-focused destination.
While the railway infrastructure and varied types of rail traffic of the early 1970s always trumped the canals for my interest, even now, if I'm somewhere with a canal in the vicinity, I'll always pop down for a good look around. Most recent occasion was on a day trip to Saltaire - I wasn't there specifically for the canal, but thought "well I'm here, so may as well have a look".