Osea Island

Osea Island sits in the River Blackwater estuary in Essex, a tidal island of around 380 acres reached by a causeway that submerges beneath the tide twice a day, lying about a mile west of Northey Island and five miles south-west of Mersea Island.

History

Its name derives from Old English, meaning “Osyth’s Island”, a reference to the 7th-century Anglo-Saxon saint whose name is attached to several places in this part of Essex.

During the First World War, Osea Island served as a base for Coastal Motor Torpedo Boats, home at times to as many as 2,000 sailors; the naval officer Augustus Agar earned the Victoria Cross while stationed there, one of the more distinguished chapters in the island’s military history. The British Army occupied the island again during the Second World War, and as early as 1913 Osea’s waters had already played a role in aviation history, hosting successful seaplane testing in the years before the First World War.

More about Osea Island

From 2005 to 2010, Osea Island housed the Causeway Retreat, a private addiction and mental health rehabilitation facility whose clients included the singer Amy Winehouse, who was treated there in 2008; the clinic later lost its registration and faced legal consequences for operating without the proper licensing, bringing an end to that chapter of the island’s history. Today Osea is owned entirely by the music producer Nigel Frieda and operates as a private retreat with its own recording studio, hosting musicians, including reportedly Rihanna in 2019, alongside film and television productions such as adaptations of The Woman in Black and the miniseries The Third Day.

Wildlife and area

Osea’s marshes and surrounding waters support Grey Seal, Harbour Seal, Common Tern and Oystercatcher, typical of the Blackwater estuary. It lies close to other Essex islands including Canvey Island and Wallasea Island, part of the same low-lying, marsh-fringed coastline.