PORTLAND, Ore. (KOIN) — A sinkhole 20 feet wide and 15 feet deep has formed at Cape Kiwanda State Natural Area in the northwest corner of the park’s sand dune.

Oregon State Parks Park Manager Jason Elkins told KOIN 6 News that Tillamook County’s sandstone outcropping is a rare and fragile geological formation for the Oregon Coast. The sandstone, he said, is naturally much weaker and more prone to sudden collapse than the isles of basalt that dot the Oregon coastline.

“The cape is a dynamic environment. Please be aware of your surroundings, stay clear of any dangerous areas, including this one,” Elkins said. “Obviously people are curious and may want to see it for themselves, but we ask that you respect the barriers that are in place and observe from a distance.”

Park staff were alerted to the sinkhole Sunday and taped off a portion of the popular whale-watching spot for safety.

Oregon Parks and Recreation Department spokesperson Stefanie Knowlton said that beachgoers are urged to keep children away from the sinkhole to prevent any sinkhole-related emergencies. Leashes are also strongly recommended for people visiting the area with pets.

“While any natural area carries risk, enjoying Cape Kiwanda safely requires visitors to pay special attention,” Knowlton said. “Even though the spot is marked with barriers, this hole could change at any moment and others could appear.”

The sinkhole remains taped off in the area. (Photo provided by the Oregon Parks and Recreation Department.)

Oregon State Parks is actively investigating the cause of the sinkhole. Citizens who come across any potentially alarming changes in the park’s landscape are asked to leave the area and report their sightings to Cape Lookout State Park by calling (503) 842-4981. Emergencies should still be reported to 911.

Oregon State Parks said that it will provide more information about the sinkhole when possible.