Canal basin Wikipedia
A canal basin is (particularly in the United Kingdom) an expanse of waterway alongside or at the end of a canal, and wider than the canal, constructed to allow boats to moor or unload cargo without impeding the progress of other traffic, and to allow room for turning, thus serving as a winding hole. For inland waterways, a basin may be thought of as a land-locked harbour.
A basin was often associated with wharves around its perimeter, to support commercial users. In modern times, canal basins are more usually used to moor residential and recreational narrowboats.