The famed hydrothermal vents and geysers found across Yellowstone National Park are impressive, but best admired at a distance. All that bubbly water isn’t carbonation, after all. A hot spring regularly reaches boiling temperatures, and their eruptions can launch scalding plumes dozens of feet into the air.

Despite these dangers, Yellowstone oversees approximately 15 miles of walkways around its famous natural attractions. But how are these routes planned, constructed, and maintained to keep the national park’s millions of annual visitors both in awe and safe? To showcase the process, Yellowstone recently shared a brief video to social media that offers a rundown of its lengthy boardwalks.

While the paths are all built by hand, mapping the routes requires a lot of preparation work. Park geologists rely on thermal cameras to identify particularly hot areas, which construction crews then avoid as they lay out new paths. However, it’s not only Yellowstone’s human visitors that need to be kept safe. Botanists also survey proposed paths to make sure any rare native plants remain undisturbed and free from damage during construction. Then there are hidden subjects to consider. Archaeologists examine routes for any ancient artifacts or historic remains buried underground, then adjust plans accordingly.

The final results are reliable boardwalks that let you get close—but not too close—to Yellowstone’s hydrothermal hotspots while also keeping the region’s native ecosystem and history intact. For more tips, be sure to check out the park’s safety website.