If you're looking to cool off, one thing you don't want to do is take a dip at the bottom of a waterfall.
Park rangers said it's not allowed, it's dangerous and can even be deadly.
As the area is in the midst of a heat wave, people are finding ways to cool off.
Some folks found cool spots at the Delaware Water Gap National Recreation Area.
"Not so bad in the trees but when you get out here, it's pretty warm," said Jane Chew of New Jersey.
"The temperature here is really nice," said Karen Milani of Massachusetts.
One way to cool off inside the park is to head to the local waterfall. There, you can feel a nice breeze and also mist coming off of the waterfall.
But one thing you're not allowed to do is get wet in the pool because the closer you get to the bottom of the waterfall, the more dangerous it becomes.
"At the bottom of the waterfall, there is hydrology that causes the water to swirl around and it can easily suck somebody in, underneath, into the deep pool," said Kathleen Sandt, a park ranger with the Delaware Water Gap National Recreation Area.
Sandt said a few years ago, a teen was killed while climbing a different waterfall in the park. He slipped and fell to the bottom of the falls.
"It actually took our rangers almost a week to recover the young man's body. From the pool at the bottom of the waterfall, because the hydraulics at the bottom of the falls, where the water hits the pool are so strong that it will suck things into it and not spit them back out for a while," said Sandt.
Park rangers said that incident is one reason people are not allowed to swim or climb the waterfalls at the Delaware Water Gap National Recreation Area.
Instead, rangers suggest visiting Smithfield or Milford Beaches, where lifeguards are watching.