The 1,029-acre Big Oak Tree State Park is an oasis of forests located in the abundance of farmland of the "Bootheel" region of southeast Missouri. Early explorers to the region discovered a unique landscape where the Ozark hills dropped off abruptly into flat flood plains covered with giant trees. Beginning in the late 1800s, the giant timber and fertile soil of the lowlands began to attract timbermen and farmers. Timbermen cleared the trees leaving bare land and landowners supported the creation of drainage districts that enabled them to plant crops, such as wheat, soybeans and corn. Over two million acres were converted from forest to cropland. In the 1930s, citizens of southeast Missouri began to realize that their magnificent lowland forests were about to disappear forever. A campaign to save a large oak tree and 80 acres surrounding it attracted statewide attention. In response, Gov. Lloyd Stark asked the Mississippi Valley Hardwood Co. to spare the tree and surrounding land. Due to the Great Depression, the state, however, could not afford to purchase the land. Despite the depression, businessmen and local citizens began donating money while area school children gave their nickels and dimes. In 1938 over 1,000 acres were purchased and dedicated as Big Oak Tree State Park.

The big oak tree that the citizens fought to save was located in an 80-acre tract of virgin bottomland hardwood forest, which is now designated as a National Natural Landmark. It stood there for nearly 400 years before dying in 1952. Today, trees in the park are unsurpassed in the state for their size, with a canopy averaging 120 feet and with several trees more than 130 feet tall. Four trees qualify as state champions in their species; with one ranking as a national champion. Ninety percent of the park is designated as a Missouri natural area because of its rarity and value in preserving this significant representation of Missouri's natural heritage. The park was declared a National Natural Landmark in 1986 because it was a rare untouched wet-mesic bottomland hardwood forest in the Mississippi Alluvial Plain, which is part of the Gulf Coastal Plain and it contains the state park system's only cypress swamp.

The park features a boardwalk that winds its way through the park past some of the park's largest trees. A walk on the boardwalk also gives visitors a chance to view many common mammals, such as deer, raccoons, squirrels and opossums, along with the rare swamp rabbit. Amid the lofty trees live more than 150 species of birds, giving the park a national reputation among bird watchers. An interpretive center along the boardwalk explains the forest and swamp ecosystem in the park. Big Oak Lake provides 22 acres of fishing. Picnic sites, a picnic shelter, and a playground are all nestled under towering trees, which makes the park a great place for a family to spend the day.