The park contains Otter Lake, which is a man-made body of water originally created by the construction of a dam.
The landscape is characterized by glacial erratics and eskers, remnants of the region's geological history.
It sits within the larger Monadnock Region, known for its proximity to Mount Monadnock.
The property was formerly part of the extensive land holdings that characterized New Hampshire's mid-20th-century state forest expansion.
The park's trail network connects to a broader system of regional snowmobile trails during the winter months.
Greenfield State Park is a 400-acre forested recreational area located in the Contoocook River Valley of New Hampshire. It features frontage on Otter Lake, offering a sandy swimming beach and boat access for non-motorized watercraft. The terrain includes an extensive trail system suitable for both hiking and winter activities like cross-country skiing. The park provides 252 individual campsites, including designated group sites and lean-tos. Visitors can access a variety of ecosystems, including pine and hardwood forests, bogs, and marshes. It serves as a primary hub for regional wildlife observation, particularly for birdwatching. The park infrastructure includes picnic areas with grills and accessible restrooms. It is situated at an elevation that creates a distinct microclimate, often cooler than the surrounding lower-lying valleys.
The wooden footbridge spanning the inlet near the northern end of Otter Lake.
Bring insect repellent, as the lakefront and wetland areas are prone to high mosquito and black fly activity in early summer.
Reserve campsites well in advance via the official state parks portal, as they reach full capacity during weekends.
Pack water shoes, as the lake bottom near the beach can be rocky in certain sections.
Do not attempt to swim outside of the designated beach zone, as underwater obstacles may exist.
Park grounds are primarily active from late spring through mid-autumn; camping facilities follow a seasonal operation window.
Carry-in, carry-out policy for all trash; pets must be leashed at all times and are restricted from the designated public beach area.
