While many of the attractions were rather sanitised (including some of the most aesthetically-pleasing piles of coal I've seen), a boat trip along the Regent's Canal was a real treat - especially as it took us through the Islington Tunnel.
In the early nineteenth century, canals were the latest transport craze (and although they would soon be overtaken by the railway craze, they continued to play a significant role in transporting freight well into the twentieth century). Thus the Regent's Canal was approved by Parliament in 1812, and the company managed - albeit with some difficulty - to raise funds for its construction. The canal opened in 1820 and among the engineering achievements involved was the construction of a tunnel over half a mile long under the streets of Islington.
It was quite a feat on the part of the canal's engineer, James Morgan. The construction was done using manual labour, helped only by explosives. Thomas Telford described it as 'materials and workmanship excellent, and its direction perfectly straight'. The fact that it is still in use two centuries later supports his positive assessment.
Of course, the disadvantage of a tunnel is that it generally doesn't have a towpath. Unable to have their barges towed along its length by horse, the barge crew had to 'leg' the boat through, lying on their backs and using their legs to push it along the tunnel length. They must have been hugely relieved when an alternative system came into operation in 1826! A steam tug heaved barges on a continuous chain, saving the efforts of their crews. Only in the 1930s was it replaced by a diesel engine, although today's barges are expected to travel through under their own power.
The tunnel has arguably increased in status in recent decades. Once the third-longest canal tunnel in the south-east, it is now the longest left in use. In former first place was Strood Tunnel, since converted into a railway tunnel, while the second-placed Greywell Tunnel closed in 1932.