Formosa Island is an island in 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,...

 in England at Cookham Lock

Cookham Lock

Cookham Lock is a lock with weirs situated on the River Thames near Cookham, Berkshire. The lock is set in a lock cut which is one of four streams here and it is surrounded by woods. On one side is Sashes Island and on the other is Mill Island connected to Formosa Island, the largest on the...

 near Cookham

Cookham

Cookham is a village and civil parish in the north-easternmost corner of Berkshire in England, on the River Thames, notable as the home of the artist Stanley Spencer. It lies north of Maidenhead close to the border with Buckinghamshire...

, 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...

, with two smaller adjacent islands.

The island is one of the largest on the non-tidal river Thames with 50 acres (20.2 ha) of woodland. It can be reached by footbridge from Cookham. It is between two of the four channels in the river at Cookham, the one closest to Cookham was once the mill stream to a paper mill at Cookham. The one on the other side leads to Odney Weir. The adjacent Mill Island has the lock channel on the other side. Beyond the lock channel is Sashes Island

Sashes Island

Sashes Island is an island in the River Thames in England at Cookham Lock near Cookham, Berkshire. It is now open farmland, but has Roman and Anglo-Saxon connections....

  and the channel furthest from Cookham is Hedsor Water

Hedsor Water

Hedsor Water is a backwater of the River Thames near Cookham, Berkshire which leaves the river above Cookham Lock and rejoins at the tail of the lock cut, running alongside Sashes Island. Hedsor Water was once the main course of the Thames but was by-passed for navigation by the construction of...

, the original navigation channel, which was blocked by the weir in 1830 when the lock was opened, causing loss of trade to then owner Lord Boston.

See also

• Islands in the River Thames
  Islands in the River Thames
  This article lists the islands in the River Thames, in England. It excludes many of the smaller lock islands that were created when weirs and locks were built, and also some very small islands that immediately adjoin the larger ones. The Isle of Dogs and Isle of Grain are no longer islands although...