Climbing permits are required for travel above 4,800 feet (tree line) year round. Between April 1 and October 31, a fee of $22 is charged for each permit. Starting February 1st, permits are sold in advance, online, through the Mount St. Helens Institute on a first-come-first-served basis. Climbers should be aware that in rare instances rock and ash from small explosive eruptions can reach the crater rim. Visit the climbing website for detailed information about volcanic hazards, safety equipment and how to purchase a climbing permit on-line.