From the start of the Grand canal at Grand Canal dock, there are seven locks until Portobello Harbour. After this there is a three km flat until the first lock main line, which is at the junction of circular line and the old James Street Harbour. St. James Harbour was the original terminus of the canal but ceased use in 1796.

In 1790 work began on linking the canal to the Liffey. The new route was to follow the newly built South Circular Road and with assistance from the government, the new circular route to Ringsend Docks were competed in 1796. Portobello Hotel was opened in 1807 and became the passenger terminus. In the 1850s it was turned into a hospital and now is a third level institution.