Fourteen thousand years ago the spot on which you are standing was covered under a mile-high ice sheet. The fourth Wisconsin glacier carved the cluster of lakes into Northwest Iowa. While this north-south cut is typical of glacial lakes, West Okoboji is unusual because it is so deep.
One theory is that a waterfall, coursing down the mile-thick ice, gouged the lake bed to its depth of 136 feet or more. Or perhaps, the juggernaut of ice, shoving glacial rubble ahead of it, sculpted the 6 1/2 mile-long basin to be filled by melting ice as the glacier retreated. Glacial deposits here are younger by hundreds of thousands of years than the glacial deposits of most other Iowa landscapes.
Special landscape formations resulted from direct contact with melting and disintegrating glacial ice. Knobs, ridges, hogsbacks, eskers, kettle holes, and fens are living imprints of some of nature's most remarkable phenomena.
Nine thousand years later there were forests here. Then the climate changed. Fires swept the forests, and prairie grasses, reeds, rushes, marshlands, and fens took over.
Beneath the waters in front of you is a canyon of deep, dark, cool water. This "lake below the lake" touches the top waters, but does not intermingle. The top lake, because of a temperature inversion of cooling and heating, turns over twice
West Okoboji Lake is spring fed, with an irregular shoreline of over 25 miles, all protected by filtering percolators in the form of wetlands. These natural factors, combined with several generations of dedicated environmentalists, have contributed to the enhanced quality of the brilliant blue water.