Visitors entering Yosemite National Park for free this week will be greeted by some of the most spectacular spring waterfalls in recent memory, thanks to an El Nino-fueled snowpack that’s 200% of normal

But they also may encounter a less savory element: scalpers auctioning the park’s coveted campsites and Half Dome climbing permits to the highest bidder, USA Today reported.

According to the Sacramento Bee, dozens of ads on Craigslist sites have offered prime camping slots this summer, marked up to $100 or $150 from the $20-per-night official cost available through the park’s contractor, ReserveAmerica.

Profiteers also are nabbing and reselling permits to climb Yosemite’s iconic Half Dome, which are issued by the park for free plus a $1.50 handling charge, the paper reports.

For vacationers hoping to reserve one of Yosemite’s 900 campsites (about the same number are first come, first served), the park accepts phone or online bookings for a desired arrival date on the 15th of the month, up to five months in advance.

“Yosemite officials urge visitors to check back often with ReserveAmerica for campsite cancellations – which can, and do, occur throughout the summer, (and) park insiders also recommend to reserve online, not by phone,” the paper says.