Columbus Metro Parks says it's dealt with about 40 thefts from cars so far this year.
One woman is already behind bars, accused of breaking into cars in one parking lot.
Park rangers say more crooks are out there waiting to take advantage of your false sense of security.
Marvin Snyder and his family spent Tuesday enjoying a picnic in the shade at Battelle Darby Metro Park. Despite the peaceful scene, Snyder says he still locked up the car.
“Absolutely. Yep. And other than walking down to see the bison the car was always in sight of where we were,” said Snyder.
Park rangers say you'd be surprised how many guests abandon caution when they arrive at the parks.
“Kids are excited cause they're going to the playground, that's not the time we want you to let down your guard,” said Larry Peck, Metro Parks Deputy Director.
Peck says so far this year, thieves have smashed into about 40 cars at the Metro Parks, and about half of those crimes happened in the past two weeks here at Battelle Darby, and nearby Prairie Oaks. Park rangers say thieves are watching visitors park their car and hit the trail.
“You know that a person is going to exit their vehicle and they're going to be gone for an hour,” explained Peck.
Some of the crimes were caught on surveillance camera, but officials say the best defense is keeping your guard up.
Rangers have a message for thieves staking out the Metro Parks parking lots.
“Stop or you're going to eventually get caught.”
There are some things park visitors should never do.
Rangers say they've observed guests leaving their cars unlocked and windows down with valuables inside. They've also watched visitors lock their purse or wallet in their trunk in the parking lot. If the thieves are watching, it's not hard to smash the window and pop the trunk button.
Finally, Peck says he's actually seen visitors who feel so safe at these parks leave their keys on their tire because they don't want to carry them on the trail. Rangers say hide your valuables before you get here, lock up, and report any suspicious behavior.