Dayton MT, Dayton, MT 59915 - Lake County

Like the cold, clear waters of Flathead Lake, mystique surrounds Cromwell Island. It overlooks the legendary Wild Horse Island, where the Salish and Kootenai Tribes historically swam their horses to protect them from rival tribes. In the 1930s, construction began on a dam near Polson, Montana, at the outlet of the Flathead River. Before its completion, Cromwell Island would sometimes become a peninsula during periods of low water. It is highly likely that Native Americans used this land bridge to herd their horses before swimming them across to Wild Horse Island. Today, Cromwell Island is a full-time island and the entirety of it is now for sale.

Flathead Lake, with nearly 200 square miles of surface area and 185 miles of shoreline, is the largest natural freshwater lake west of the Mississippi River yes, even bigger than Lake Tahoe. Cromwell Island, spanning nearly 350 acres with almost three miles of shoreline, is believed to be the largest private freshwater island west of the Mississippi held under a single ownership.

Like Loch Ness, Flathead Lake even has its own monster. Rooted in the ancient oral traditions of the Kootenai Tribe, tales of a massive, antlered lake creature date back centuries. The first recorded sighting came in 1889, when a steamboat captain and 100 passengers reported seeing a “whale-like” object that dove after being shot at. Locals eventually dubbed the creature “Flessie” a playful nod to her Scottish counterpart.

Cromwell Island was purchased in the late 1980s by Robert M. Lee, a renowned automobile and antique arms collector, explorer, author, and conservationist. Before his passing in 2016, Mr. Lee and his wife, Anne, began construction on a monumental residence of over 45,000 square feet intended as their full-time home. Even in its unfinished state, the structure commands a presence reminiscent of Versailles.

The mystique endures. Cromwell Island is now for sale, offering a rare opportunity for a new owner to write the next chapter of a truly storied place.