Hverir is a high-temperature geothermal area with fumaroles and mud pots that bubble to a temperature of over 200 degrees Celsius.
Not far from one the more popular hot springs in North Iceland, the Hverir Geothermal Field is one of the most spectacular (and overlooked) places in all of Iceland. The fields consist of mud pots that bubble and produce high temperature steam from the extreme heat underneath being released into the air.
If you are coming from the nature baths, drive 3km ahead and around the mountain in front of you, and Hverir will be on your right, you can't miss the steam. You're free to walk on any paths around the mud pots, but please please do not walk off the path. I would highly recommend bringing waterproof boots. If you just bring tennis shoes, they will most likely get stuck in the mud. If you want to capture the mud pots up close, I'd recommend bringing a waterproof camera just to be safe.
Other than that, have fun exploring! Parking and entrance is completely free. It definitely feels like you're on another planet when you're walking around Hverir.