Lake Sunapee is located within Sullivan County

Sullivan County, New Hampshire

-Demographics:As of the census of 2000, there were 40,458 people, 16,530 households, and 11,174 families residing in the county. The population density was 29/; . There were 20,158 housing units at an average density of 38 per square mile...

 and Merrimack County

Merrimack County, New Hampshire

-Demographics:As of the census of 2000, there were 136,225 people, 51,843 households, and 35,460 families residing in the county. The population density was 146 people per square mile . There were 56,244 housing units at an average density of 60 per square mile...

 in western New Hampshire

New Hampshire

New Hampshire is a state in the New England region of the northeastern United States of America. The state was named after the southern English county of Hampshire. It is bordered by Massachusetts to the south, Vermont to the west, Maine and the Atlantic Ocean to the east, and the Canadian...

, the United States

United States

The United States of America is a federal constitutional republic comprising fifty states and a federal district...

. It is the fifth-largest lake located entirely in New Hampshire.

The lake is approximately 8.1 miles (13 km) long (north-south) and from 0.5 to 2.5 mi (0.80467 to 4 km) wide (east-west), covering 6.5 square miles (16.8 km²) , with a maximum depth of 142 feet (43.3 m). It contains eight islands (Great Island, Burkehaven Island, Star Island, Little Island, Loon Lighthouse Island, Emerald Island, Treasure Island and Minute Island) and is indented by several peninsula

Peninsula

A peninsula is a piece of land that is bordered by water on three sides but connected to mainland. In many Germanic and Celtic languages and also in Baltic, Slavic and Hungarian, peninsulas are called "half-islands"....

s and lake fingers, a combination which yields a total shoreline of some 70 miles (112.7 km).