Complex sentence: The lower reaches of the river are navigable to river craft and are known as the Kennet Navigation, which, together with the Avon Navigation, the Kennet and Avon Canal and the Thames, links the cities of Bristol and London.
Split into simpler sentences: The lower reaches of the river are navigable to river craft and are known as the Kennet Navigation. This, together with the Avon Navigation, the Kennet and Avon Canal and the Thames, links the cities of Bristol and London.