The annual lottery for coveted, self-guided river trips through the Grand Canyon opened Sunday.

Applications for the trips on the Colorado River will be accepted through Feb. 24.

Grand Canyon officials say 472 permits will be available for the 12- to 25-day trips. The permits are for specific launch dates in 2016.

Additional draws are held for trips that are canceled or left over after the application deadline.

The lottery costs $25 to enter. Winners are subject to additional fees.

The main applicant must be at least 18 years old. A least one person on the trip must be experienced in whitewater rafting.

Those who are drawn can participate in only one commercial or self-guided river trip per year.