You can tell right off the bat, "Hero Rush" in Round Rock isn't your typical 5k run on smooth level asphalt.
The nearly 2,000 people who showed up to Hero Rush were looking for something a little more challenging.
"I've done some obstacle races, mud races down in the Rio Grande Valley. But they've never been as cold as this. And I've got to say this was hard," said Larry Prater from McAllen.
All of the 18 obstacles over 4 miles are based on some of the same stuff firefighters go through...like the "towering inferno." Contestants crawl up the black tubing they call raining stairs and then slide down a water slide.
Event director Stuart Kaul says Hero Rush was actually started by a couple of firefighters.
"One of them ran one of our competitor's races and as a firefighter said, 'Gosh what we do in training in some of our calls is harder than what I just did right here! And so I'm gonna create my own race,' and so he created Hero Rush along with one of his partner firefighters," Kaul said.
Eric Ortega is a firefighter from the San Antonio area. He was pretty impressed.
"Well you've got a lot of ladder work, you've got a lot of enclosed space work, carrying hoselines up hills, down hills," Ortega said.
Contestants also had to swim in the windy 55 degree weather.
"The hardest part is probably the river swim. Once you get in there completely you just shock up! Completely lock up," Ortega said.
"We have them swimming across a lake and going through a creek. But you know what, they love it. They knew that it was gonna be a little chilly but the fact that they're actually completing the obstacle, they trained for it...and they completed the course. When they're done, they're like 'Yes I did it,' Kaul said.
Hero Rush wasn't all fun and games. It was also for a good cause. Part of their proceeds are going to the National Fallen Firefighters Foundation.