Western Canada might not exist if it hadn't been for canals.

After the war of 1812, Canada / Britain (there wasn't really a separate Canada at that point) decided there needed to be a way to get military supplies and equipment to Fort York (Toronto) and west of there without using the St. Lawrence river. The river had a number of issues, but the biggest one was that the US controlled the southern shore. So, as a result, it built a canal from Ottawa to Kingston. Montreal to Ottawa was possible with existing rivers, and it was safe to get to Montreal from England without going too close to US territory.

So, the Rideau Canal was built. It connected Bytown (now Ottawa) to Kingston. For about 30 years it was the main way of moving people and supplies to the upper shore of Lake Ontario. After that it was replaced by railroads. But, without all the people who had moved west thanks to the canal and now could buy and sell things, there might not have been the justification to build those railroads.

So, yeah, it got outpaced by technology. But, it was a good idea, and was very useful for a few decades.

Also, many of those canals are now tourist attractions and pleasant natural spaces for residents. Virtually everywhere I've travelled where there is a canal, it is now used by people for pleasure boating, or houseboats. Almost always there's also a nice walking path or bike path next to the canal. Rivers are lovely, but rivers tend to have sloped banks which means there isn't a natural path that's right next to the water. With canals, there's often a man-made edge to the waterway, so you can walk / bike right next to it.