Seaman Reservoir is a reservoir and protected area northwest of Fort Collins, Colorado, about 15 miles up the Poudre Canyon. Also known as the Gateway Natural Area, it is shaped by the canyon landscape around the water. As reservoir levels change, the surrounding cliffs can stand from about 6 to 70 feet above the shoreline, giving the area a distinctly different appearance under changing conditions. A short Seaman Reservoir Trail extends 1 mile one way with almost no elevation gain, providing a relatively level route through the site.