JIM THORPE, Pa. (AP) — Katelyn Carlisle nervously eyed the murky waters lapping at her feet.

"It's quick. You gotta swim. You can swim, right?" her friend, Chris Manzi, 23, quipped from the opposite riverbank. With that, Carlisle, 25, jumped into the Lehigh River and began stroking her way to the other side.

Neither of them knew that section of the river had recently claimed two lives in 10 days. Nor had they spotted the warning signs that officials at Lehigh Gorge State Park installed in response: "Notice, dangerous currents, not a designated swimming area."

As temperatures rise, people are inexorably drawn to water. But several recent drownings highlight anew the hot-weather danger posed by Pennsylvania's tens of thousands of miles of rivers and creeks, where deceptively strong currents, underwater obstacles and steep drop-offs can make for a deadly combination. Five people have drowned in state park waterways alone so far this year, matching the total for all of 2017.

Tragedy hasn't been confined to the state parks. A 7-year-old boy waded into central Pennsylvania's Pine Creek on Tuesday, got out of his depth and drowned. His mother died trying to save him.

"Even people who know rivers and streams can step into a hole and all the sudden you are over your head," said Terry Brady, spokesman for the state Department of Conservation and Natural Resources.

Manzi and Carlisle — who live in Denver and Milwaukee and were in Pennsylvania for work — entered the water with a group of co-workers on a cloudless afternoon last week.

The current, at least on the surface, seemed relatively tame. But the river still posed a slight challenge for Carlisle, who had never swam across one before. She paddled in place for several seconds before breaking free of the current and making it to calmer waters.

"I'm swimming hard and I'm not going anywhere," she explained after getting out. "I kept telling myself, 'Swim harder, swim harder.'"

A few weeks earlier, two other swimmers weren't as fortunate.

On June 19, 24-year-old Angel Rivas, of Hazleton, drowned as he and his friends swam across rapids. Then, on June 29, the Lehigh took Jersson Lajara of New York. His body was recovered a day later.

Jim Thorpe Fire Chief Vince Yaich is frustrated by the situation at Lehigh Gorge, a popular state park in the mountains of northeastern Pennsylvania, 100 miles (161 kilometers) north of Philadelphia.

He said his department is called to Lehigh Gorge an average of 10 times a year, mostly to rescue people injured near the park's Glen Onoko Falls, but also to recover the bodies of drowning victims.

Yaich said the state should do more to keep swimmers out of the river by issuing tickets to violators.

"If there's no swimming, like the park is saying, then enforce it. Don't just put up a sign," he said. "You catch somebody in there swimming, you fine them. End of conversation."

Park manager Rex Bradish said it's not that easy. There are jurisdictional complications, and the state prefers education over enforcement.

"These types of tragic events are never something we want to see, and if we can prevent them through increased patrols and signage, and engaging visitors and educating them, that is the way we want to go," he said.

The temporary signs near the river do not explicitly state that swimming is banned, only that it's "not a designated swimming area" — which has the same meaning under state law but could sow confusion among park visitors. State officials say they plan to re-evaluate the wording.

Signs or not, at least two groups of visitors — teenagers from the Philadelphia suburbs and the out-of-state colleagues that included Manzi and Carlisle — swam across the Lehigh in the span of a couple hours last week. Most said they didn't think twice about going in.

Had he spotted the warning sign, Ben Mills would have taken it as a challenge.

"It's the cookie jar syndrome," said Mills, 35, of Atlanta. "You want what you're not supposed to have."