A man has been rescued after falling 800 feet down the sheer walls of Crater Lake National Park, the caldera of a dormant volcano in southern Oregon. A U.S. Coast Guard helicopter hoisted the man to safety Monday afternoon, according to a release from the agency.

The helicopter responded after a rope rescue team lowered 600 feet down the cliff face but was unable to reach the man. "The District 3 team reported they could hear a man yelling from further down into the caldera," the Coast Guard said.

National Park Service officials requested helicopter assistance.

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The man was transported to a hospital in unknown condition, but was able to walk after the rescue, according to the Coast Guard.

In a separate online message, the National Park Service warned of the danger of the steep caldera walls, in places rising nearly 2,000 feet above the lake surface.

In a Facebook post, Crater Lake National Park posted images of the rescue. "A big THANK YOU to all who helped in this effort!" the Facebook post read.

In a subsequent Facebook post, Crater Lake National Park gave this advice: Don't get too close.