Freda Haffner Kettlehole is a 110-acre preserve containing the largest glacial “kettlehole” in Iowa, created by the melting of a block of glacial ice some 13,000 years ago. A highly diverse native prairie community is also found here. It is located 2 miles west of West Okoboji Lake, approximately 4.5 miles northwest of Milford in Dick­inson County. Once known as “Arend’s Kettle Hole” and the “Big Kettle,” the first 12.4 acres were given to the Iowa chapter of The Nature Conservancy in 1972 by local conservationist Freda Haffner. The area was dedicated as a biological and geological state preserve in 1976.