Loved the canals when I lived in England (Leeds). I didn't narrowboat, but rode bike (including commute) on the canal sidewalks.

Canals tend to have wildish nature around them (quite rare in England) and they are digged totally flat (with a very subtle incline/decline, apart from waterlocks). They have decent sidewalks that make them ideal to bike along (quite rare in England). They are very long so you can have a daytrip to visit multiple towns. And they don't have cars (quite rare in England).

Canals are great!