"The growing size indicates the debris used to seal the mine shaft 50 years ago has deteriorated. Anyone stepping into the depression to get a closer look at the hole could fall through the thin crust of dirt overlaying the mine opening."
Bobbi Wallace of King County Parks "worries about mountain bikers and geocachers — people who take part in scavenger hunts using handheld Global Positioning System (GPS) units.
"In their eagerness, they often go through the underbrush instead of staying on designated trails, she said."
Mind your step. "There isn't an emergency crew in the county that can rescue you if you fall into an old mine."
Edit: adding Snakes in a Mine. And line breaks.