Peninsula is the third largest state park in Wisconsin and is visited by an estimated one million visitors annually.

The primary purpose of building a state park in the northern part of Door County was to afford a playground and resting place for those whose financial conditions and locations precluded the possibility of owning summer cottages.

The park was originally free and did not charge admission in order to achieve the purpose of keeping visitors' expenses to a minimum, so that toilers would be permitted to share in the pleasure and benefits of outdoor life.

Early projects included miles of roads, scenic lookouts, campgrounds, two towers, and initial portions of two golf courses.

Around this time, Doolittle established Door County Days, a summer picnic with music and sports events attended by thousands.

A Civilian Conservation Corps camp was established at Peninsula State Park during the Great Depression.

[9][10][11] The prisoners engaged in construction projects, cut wood, and picked cherries in the park and surrounding area.

[12] In 1982, Sunset Bike Trail was surfaced, computers began to be used for reservations, and an irrigation system was installed on the golf course.

Considered Wisconsin's most complete park, Peninsula has 468 campsites, three group camps, a summer theater, an 18-hole golf course, sand beach, biking, hiking and ski trails, 150-foot bluffs, a lighthouse and eight miles of Door County shoreline.

The White Cedar Nature Center features a display of mounted animals, as well as historic photos and artifacts, and a large diorama of the park.

The building was constructed in 1939 as a winter warming house for the nearby ski jump and toboggan run, both abandoned in the 1940s.

[14] Another tower stood in the park at Sven's Bluff from 1914 to 1947 but was dismantled due to poor condition and never replaced.

[18] Northern Sky Theater (Formerly American Folklore Theatre) is located within Peninsula State Park.

[19] It has no establishments other than a pit toilet, a hiking trail and the foundations of buildings once occupied by the Folda family in the 1890s.

Sunset Bike Trail provides a safe and scenic alternative to Shore Road for bikers and hikers.

In 1921 The Door County Country Club opened for play as a six-hole golf course, functioning with “sand and oil” greens during its first ten years.

The park's sandy swimming beach—popular with campers and very crowded during warm summer days—is located at Nicolet Bay.

Welcker's is popular among campers with tents and small trailers because of the heavily wooded nature of the surrounding forest.

It is also at the head of many hiking and biking trails (including a path to Nicolet Beach) and has a reservable shelter just outside the campground, which is a popular place for visitors to view bats 30 minutes after sunset during summer evenings.