This is a list of the Sites of Special Scientific Interest (SSSIs) in Merseyside, which is part of North West England. Merseyside has a population of 1,353,600 making it one of the most densely populated areas of the United Kingdom. Geographically, Merseyside is split by the River Mersey which has a surrounding network of canals, rivers and valleys some of which have been created by human activity. Other habitats have been adversely affected by humans including many peat mosslands. As of 2007, There are 14 sites designated within this Area of Search, of which 10 have been designated due to their biological interest, 1 due to its geological interest, and 3 for both biological and geological interest.