Lower Horse is a 31.1-acre (12.6 ha) uninhabited island off the English coast, lying in the Thames Estuary between Canvey Island and Stanford-le-Hope, close to grid reference TQ760828.

It is part of Thurrock unitary authority; an internal border of its historical and ceremonial county Essex, namely of the administrative county of Essex is between it and Canvey Island.

Within, smaller than normal marks for a patch of saltings (traditional, open air, sea salt extraction through drying) feature in the leading map of 1919, which confirms the island's acreage.

Consisting of permanent marshland with six small internal creeks draining to the north; Lower Horse is part of the group of islands (five of which later re-clustered to form Canvey Island), that broke away from the English coastline in the medieval period.

• Islands in the River Thames

• Map showing location of Lower Horse

Next island upstream	River Thames	Next island downstream
Chiswick Eyot Note: Frog Island and Isle of Dogs are peninsulas	Lower Horse	Canvey Island

51°31′00″N 0°32′07″E / 51.51670°N 0.53520°E / 51.51670; 0.53520