Tim Keiderling and Esther Keiderling, both of Ulster Park, New York, set out to hike the summit on Sunday, officials said.

The terrain rises sharply. The trails scramble over steep rocks. Be prepared when climbing to Maine's highest point, experts advise.

Tim Keiderling, 58, and his daughter, Esther Keiderling, 28, disappeared Sunday while hiking on Mount Katahdin.