Merseyside is divided into two parts by the Mersey Estuary , the Wirral is located on the west side of the estuary , upon the Wirral Peninsula and the rest of the county is located on the east side of the estuary .
Merseyside is divided into two parts by the Mersey estuary : the Wirral is on the west side of the estuary upon the Wirral Peninsula ; the rest of the county is on the east side .