For British Inland Waterways Canal Enthusiasts. Unique Canal Route Map Mugs. Enjoy your 'cup of your fancy' as you cruise along in your narrowboat, glancing at your cup every now and again, to discover when the next lock, bridge, aqueduct, town, etc. is coming along. Top of the mug is the traditional 'harlequin' or 'joker' diamond design of canal boats on the inland waterways of the UK.