[8] Most of the area immediately surrounding the island consists of saltmarsh and mudflats, and is an important sanctuary for wading and migratory birds.

The Old City in the southwest of West Mersea serves the fishing and yachting industries and contains a number of listed buildings.

[17] A large Romano-British round barrow near the Strood contained the remains of a cremated adult in a glass urn, within a lead casket,[23][24] now in the local Mersea Museum.

[25][26] The Anglo-Saxons established a large fish weir at Besom Fleet to the southwest of the island[27] and built the church at West Mersea.

[29][30] By 950, there was a Benedictine priory at West Mersea and land here was granted to the Abbey of St Ouen in France by Edward the Confessor in 1046.

[33] The church and hall are surrounded by a moat that is thought to be the remains of a Danish refuge after their defeat by King Alfred at Farnham.

[34] In 1547, King Henry VIII built a blockhouse or bulwark at East Mersea, an earthwork fort for up to six guns with a drawbridge.

[35] In the English Civil War, it was taken in 1648 by the Parliamentary Army, with the aim of blockading the River Colne during the siege of Colchester.

Smugglers favoured the Peldon Rose, immediately north of the Strood, where they would store contraband in the pond alongside the inn.

[44] In 1926, West Mersea became a self-governing urban district, which allowed it to set up a self-contained water and sewer system.

[47] Unlike several other coastal resorts, the island did not immediately develop any holidaymaker facilities aside from the beach huts which now stretch along the Esplanade.

[46] At the outbreak of World War II, the island became part of the front line for invasion and was heavily fortified.

Along with other coastal resorts, the island drew in evacuees from London, though as the war progressed, these were moved to safer settlements further inland.

[47] After the war, the island suffered from severe winter weather in 1947 which destroyed much of the oyster fishery, and from the flooding of 1953, where numerous beach huts were swept out to sea.

[52] On 4 June 2012, as part of the Queen's Diamond Jubilee celebrations, the island declared a mock independence from the UK for that day.

Anyone travelling to the island across the Strood paid 50p for a "passport", the proceeds of which went towards the war veteran charity Help for Heroes.

[47] In 2012, West Mersea Lifeboats complained to Essex County Council about the lack of adequate signage after 13 people had to be rescued from the Strood at high tide in less than 24 hours.

[59] A webcam provides a live view of access across the Strood, while a corresponding website lists upcoming high tides and the likelihood of obstructing the road.

[61] In 1911, local businessmen proposed a railway between Colchester and the island, which would have ended at a pier next to the Esplanade in the south, with an additional station in West Mersea on what is now East Road.

[43] Baring-Gould was the writer of the hymn "Onward, Christian Soldiers" and the author of the novel Mehalah: A Story of the Salt Marshes which was set in Mersea.

[66] During the week, starting on Monday, there are races for many boat classes in the Blackwater Estuary, from Optimist dinghies to large yachts.

The most celebrated event is the Round-the-Island race, where dinghies attempt to sail round the island in either direction, helped over the Strood by volunteers.

[66] One of the popular events on Saturday is walking a greasy pole rigged over the side of the hosting Thames sailing barge.