Three visitors to Yellowstone National Park were sentenced last month to short jail terms for unrelated misdemeanor violations, federal prosecutors said, emphasizing the need for safety on protected parkland.

Two visitors who strayed from clearly marked paths or roads in thermal areas at the park were each sentenced to seven days in jail, the U.S. Attorney’s Office for the District of Wyoming said late last month. A third visitor was sentenced to 10 days for driving under the influence of alcohol in the park, the office said.

The three were sentenced for public land violations that happened last fall, and their terms were handed down just weeks before the peak tourist season begins at Yellowstone, most of which is in Wyoming.

“The No. 1 priority is public safety, but natural resources are also important in places like Yellowstone National Park,” Lori Hogan, a public affairs officer with the U.S. Attorney’s Office in Wyoming, said in an interview on Tuesday.

“More dangerous offenses, like thermal trespass or wildlife disturbance, could potentially lead to jail time, while minor violations might result in fines or warnings,” she said. “The public should understand the violations and their consequences before visiting.”

Walking on the thermal grounds at Yellowstone can be extremely dangerous, park officials said, because the ground is fragile and thin, and scalding water just below the surface can cause severe or fatal burns.