Located in Central New Hampshire, 552-square-mile Sullivan County is one of the ten biggest counties in the state. The most common type of land for sale by combined acreage in Sullivan County is residential property. Browse all waterfront property for sale in Sullivan County on the Land Network to find the marina, lakefront and other recreational property that meets your needs, from waterside land perfect as a retirement investment to existing residential waterfront land and property for hunting, fishing and other outdoor-recreation pursuits!