From Aldwarke the River Don flows northwards past the Aldwarke steel works. Unfortunately the public footpath carries on down the lane by Asda, round the back of the sports ground and out onto Doncaster Road. The route of the old towpath seems to have been lost to public usage, a small remnant is shown on one of my maps but disappears into oblivion at either end.
At Kilnhurst the Kilnhurst Cut leaves the river and both river and canal run on roughly parallel courses northwards. The cut here is very wide so there must have been extensive traffic along the canal at one time. Certainly old maps show mines, factories and works all along here: some are still around, but some are gone. There is a pleasant walk along the towpath from Kilnhurst Bridge along the cut, but you can no longer follow it up towards Swinton Bridge. The towpath is blocked off south of Waddington's boatyard with a locked gate saying "KDAA Members only".
Just south of Swinton Bridge the canal is joined by the remains of the Dearne and Dove Canal before turning eastward towards Mexborough. The canal (and the river) leave the Borough of Rotherham just south of the town. You can continue your canal trip but not here.