There is a weir a little upstream at the top of the island where Sonning Backwater separates from the main course of the river.
This was the highest upstream of the eight locks constructed after the Thames and Isis Navigation Act 1750 (24 Geo.
One of his works The Thames from Oxford to Windsor is a rhymed list of the locks, bridges and towns.
Access to these is on the upper part of the reach, opposite the entrance to the River Kennet at Blake's Lock.
There are navigation transit markers just downstream of the entrance to the Thames & Kennet Marina, to allow river users to check their speed.
"The floral tastes of the lock-keeper generally make Sonning Lock very bright and gay."