Welcome to Nascar on ice. Across Minnesota, locals are racing DIY cars around tracks on the thick frozen lakes, careening and colliding at speeds up to 60 mph. Photographers Jenn Ackerman and Tim Gruber are right there in the middle of it, even hopping into the passenger seat for that perfect shot.

The Minneapolis husband and wife team first learned about the sport in 2013. They came across a cardboard sign with the words "Ice racing” scrawled across and an arrow pointing towards a nearby lake. The pair decided to investigate, and burst upon a dozen or so cars barreling across the frigid tundra. They knew they had to find out more. “It was pretty organic,” Gruber says. “Just stumble upon a sign and next thing you know, there’s your next project.”

The pair have since photographed around 10 racing events around northern Minnesota for their series Frozen Speed. While there is an official organization for the sport, Ackerman and Gruber prefer to document the laid-back environment of smaller, more off-beat races. Most occur between January and March when the ice is an ideal 18-inches thick, and last around three hours. Since the unofficial race schedules can be random, Ackerman and Gruber rely on racers to find out when the next event will be.

One location is Garfield Lake, a 1.5 square-mile body of water near Laporte, Minnesota. Race day usually starts around noon, with a half mile “track” carved out by a truck with a small plow. Both photographers admit they were initially a little nervous standing in the middle of a frozen lake with nothing but a layer of ice under their feet. “A part of you questions your sanity, all these vehicles and heavy trucks parked so close to one another on a lake. Is this actually safe?” Gruber says, “But, after you do it, you kind of forget you’re on a frozen lake.”

The race car of choice is usually heavy duty sedan like the ‘85 Imapala or Caprice decked out with studded tires. Many sport racing numbers and boast names like “Ice Is Nice” and “The Sh*t Show.” But the decor doesn’t end there–one driver roped a massive, purple monkey to the top of his car and another stuffed duck.

After a couple of practice laps, the races begin. A volunteer waves a flag to signal the start and another keeps tally of the lap times from the comfort of a warm car. Around 10 cars hurtle and slip around the track, sometimes making contact. The event is usually three small heats and then a final where top finishers do a 15-lap race. At the end of the day, a winner is declared and many racers head to the local watering hole to rehash the day’s excitement.

Ackerman and Gruber have numerous ways of getting in on the action. They use five different cameras, including a GoPro mounted directly onto the car and a lightweight Sony camera attached to a remote control quadcopter for stunning aerials. Ackerman’s even hopped into the passenger seat and gone for a spin herself. “You get in the car and they think it’s just like nothing, and I’m breathing heavy, freaking out the whole time,” she says.

Though cars sometimes collide, the photographers never witness anything more dangerous than a fender bender. After the final race, everyone clears out quickly to get indoors away from the frigid weather. The fun is over. “The fact that people elect to do this on a Sunday afternoon when it’s -40 out there and they could be in a nice, warm house is sort of a testament to their love of the sport,” Gruber says.