A view of Sheep Lakes in Rocky Mountain National Park.

(Courtesy of NPS)

The nonprofit advocate of Rocky Mountain National Park announced a campaign Wednesday to raise $3.6 million to buy the last significant island of private property within the park. 

Rocky Mountain Conservancy is eyeing up Cascade Cottages, just a mile inside of the park's popular Fall River entrance. Cabins on the 40-acre property have hosted vacationers since the 1920s.

The current owners chose to honor the wishes of their grandfather when they gave Rocky Mountain National Park the chance to buy the property before putting it on the open market.

Meanwhile, the National Park Service has called the acquisition its highest priority ahead of the park's 100th anniversary.

 Rocky Mountain Conservancy has raised $1.5 million toward its goal as of Wednesday. The organization hopes to transfer the property to the park in 2017.