Hennerton Backwater is a narrow backwater

Backwater (river)

A backwater is a part of a river in which there is little or no current. It refers either to a branch of a main river which lies alongside it and then rejoins it or to a body of water in a main river which is backed up by an obstruction such as the tide or a dam.-Alternative channel:If a river has...

 of the River Thames

River Thames

The River Thames flows through southern England. It is the longest river entirely in England and the second longest in the United Kingdom. While it is best known because its lower reaches flow through central London, the river flows alongside several other towns and cities, including Oxford,...

 on the reach above Marsh Lock

Marsh Lock

Marsh Lock is a lock and weir situated on the River Thames in England near Henley-on-Thames, Oxfordshire. The lock is close to the Berkshire bank, but accessed from the Oxfordshire side via two long walkways, the downstream one being near Mill Meadows...

 near the villages of Shiplake

Shiplake

Shiplake is a village and civil parish about south of Henley-on-Thames in Oxfordshire, England on the River Thames.-History:The Church of England parish church of St. Peter and St. Paul dates from at least the 13th century, but in 1869 the Gothic Revival architect G.E. Street rebuilt the chancel,...

, Oxfordshire

Oxfordshire

Oxfordshire is a county in the South East region of England, bordering on Warwickshire and Northamptonshire , Buckinghamshire , Berkshire , Wiltshire and Gloucestershire ....

 and Wargrave

Wargrave

Wargrave is a large village and civil parish in the English county of Berkshire, which encloses the confluence of the River Loddon and the River Thames. It is in the Borough of Wokingham...

, Berkshire

Berkshire

Berkshire is a historic county in the South of England. It is also often referred to as the Royal County of Berkshire because of the presence of the royal residence of Windsor Castle in the county; this usage, which dates to the 19th century at least, was recognised by the Queen in 1957, and...

.

Hennerton Backwater leaves the River Thames at the Unnamed Eyot

Unnamed Eyot

The Unnamed Eyot is an island in the River Thames in Berkshire, England, near the villages of Shiplake, Oxfordshire and Wargrave, Berkshire. It is on the reach above Marsh Lock....

, passing through Willow Marina, and rejoins just below Ferry Eyot

Ferry Eyot

Ferry Eyot or Ferry Ait is an island in the River Thames in England near the villages of Shiplake, Oxfordshire and Wargrave, Berkshire. It is on the reach above Marsh Lock....

. It is navigable by small boats from the downstream end for much of its length, but the bridge carrying Willow Lane over its upstream end has very limited clearance restricting passage to canoes and small dinghies even under favourable conditions.

The island formed by the backwater and the Thames comprises Wargrave Marsh (now mostly drained) and Lashbrook Eyot (no longer distinct), and contains housing, farmland, and the premises of Henley Sailing Club.