North Idaho is riddled with abandoned mines, and many of those who find them are people out and about on all terrain vehicles. But how do you know if it's safe?
In their prime, miners chased veins of lead and silver every which way they ran, which means a straight forward tunnel can drop into a vertical shaft without warning.
Once a mine shuts down those shafts can quickly fill with water. In fact, the majority of people who die in abandoned mines don't fall - they drown. But there are plenty of other hazards.
"If they go into an old mine and it's got timber and they happen to bump into it, it could fall down on top of them," said tour guide Wally Dreher with Sierra Silver Mine. "And if you've got rotten timber you can have methane gas."
Some of these old mines are well marked on maps, but the majority are located on private property and only marked if the land owner does so.
"The best thing to do is just stay out of them," Dreher said. "Don't go in."
If you want to take a safe and guided tour of a mine, Dreher can take you into the still operational Silver Valley Mine. That mine is open to the public until October 6.