Which English peninsula lies between the Dee Estuary and the Mersey Estuary?

The English peninsula between the Dee Estuary and the Mersey Estuary is the Wirral Peninsula.

The Wirral is a roughly rectangular projection in North West England. The Dee Estuary forms its western boundary, the Mersey Estuary its eastern boundary, and Liverpool Bay and the Irish Sea lie to the north. The peninsula is about 15 miles long and 7 miles wide, although its exact southern boundary can vary depending on whether the geographic or cultural Wirral is meant.

Historically, the area belonged to Cheshire and was recorded as the Hundred of Wirral in the Domesday Book. Its position beside the ports of Chester and Liverpool shaped its development. Dee-side ports such as Parkgate and Neston later declined as the Dee silted up and Liverpool’s deeper Mersey harbor grew in importance.

The Wirral is often confused with nearby English coastal peninsulas such as Holderness and the Fylde. It is also not an island in the ordinary geographic sense, though the Shropshire Union Canal’s route can be treated as part of a boundary that technically separates it from the surrounding mainland.