Big Arm State Park is located on Flathead Lake, the largest natural freshwater lake in the western United States. Twenty-eight miles long and 15 miles wide, Flathead Lake is renowned for its fishing. 

Located on the lake's Big Arm Bay, this State Park's long pebble beach is popular with sunbathers and swimmers. Camping under a stand of mature ponderosa pine and juniper is a major attraction. The hiking trail provides excellent vistas of surrounding mountain ranges and high peaks with abundant watchable wildlife opportunities. Other opportunities include: fishing for lake trout, board sailing, boating, swimming, camping, picnicking, bicycling, hiking the 2.5 mile trail, wildlife viewing, scuba diving, and water-skiing.

This site is 2,953 feet in elevation and has 217 acres. There are seven tent sites available, and 41 RV/trailer sites. Size is limited to 30 feet. Bear resistant storage lockers are also available.

Big Arm State Park now has the latest in circular camping comfort, a 20-ft wide, 10-ft tall yurt. You only need to bring bedding, cooking utensils, personal toiletries, a flashlight and a container for water. Electrical outlets, lights, electric heat and a propane barbecue for outdoor cooking are also provided. A joint state/tribal fishing license is needed for fishing at this park and campers may stay only 14 days during a 30 day period. Pets are required to be on leashes.

Big Arm is a popular jumping-off point to Wild Horse Island State Park, a 2,163 acre island off the west shore of the lake that is home to bald eagles, bighorn sheep, yellow-pine chipmunks, and wild horses. Wild Horse Island is accessible only by boat.