The Sheffield and South Yorkshire Navigation (S&SY) is a system of navigable inland waterways (canals and canalised rivers) in South Yorkshire and Lincolnshire, England. Chiefly based on the River Don, it runs for a length of 43 miles (69 km) and has 27 locks. It connects Sheffield, Rotherham, and Doncaster with the River Trent at Keadby and (via the New Junction Canal) the Aire and Calder Navigation. The system consisted of five parts, four of which are still open to navigation today:-