Offering a mix of rural-residential properties and recreational land for hunting and other uses, Sullivan County is located amidst New York's scenic Catskills Mountains.? Sullivan County is in Southern New York. Of the 62 counties in the Empire State, Sullivan County is 23rd in terms of its size (996 square miles). 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!