Underhill State Park, State park and historic site in Underhill, Vermont.

Underhill State Park sits on the western side of Mount Mansfield and covers a large forested area with hiking trails and camping spots. The park has several routes that lead toward the mountain's ridge and others that wind through the terrain at lower elevations.

Workers from the Civilian Conservation Corps built many of the park's trails and facilities in the 1930s. This historical work eventually led to the park's listing on the National Register of Historic Places.

The park's name comes from the town of Underhill, and its west slope has drawn tourists since the mid-19th century, when The Halfway House hotel lodged and stabled travellers heading up Mount Mansfield. Its foundation can still be seen. CCC crews also planted groves of Norway spruce that stand in the park today.

The park is open during the warmer months and provides restrooms, water, and picnic areas for visitors. The trails are passable year-round, but the camping sites and main facilities operate only during the peak season.

The Halfway House, a small hotel built in 1858 to lodge and stable tourists climbing Mount Mansfield, stood in what is now the park; it was demolished in 1939 and only its foundation remains. CCC crews also planted groves of Norway spruce here in the 1930s.