Take a break from the brown cafes and coffee shops for a private canal boat tour. Stag weekends can be pretty hectic so take a load off and cruise a network of canals in comfort on a private barge complete with on-board bar.
Keep it clean or add a stripper if you reckon it would be bad form not to give the groom a traditional send-off!
You will spend a couple of hours drifting down the canals, past the ornate merchants' houses, bridges, 17th century gables, houseboats and churches. This is the best way to see all the important stuff in one hit.