Hike a nine-tenths mile trail that descends to the second-largest spring in Missouri, Greer Spring, which has an average daily flow of 222 million gallons. Look for the trailhead sign on Route 19, eight miles north of Alton. Homesteaded by Thomas Simson in 1845; purchased by Samuel Greer in 1859. Activities include picknicking, floating, canoeing, boating, fishing, camping, biking trails, a backpacking trail and equestrian trails. On-site parking and vault toilets are available.