Hverir

"Once you start smelling rotten eggs--you'll know you're in the right place. This is a larger geothermal area that can be experienced in a number of ways. There is a paid parking lot which Google/Apple maps will take you to. Here you can walk around a larger area of sulfurous mud springs and fumaroles, though you'll more than likely be amongst a very large group of tourists. We recommend stopping at the free small, unofficial parking lot up the hill off to the right before you reach the main parking lot. From here you can take a number of different paths, one of which leads down to the more popular area, and another which leads you up higher to a vantage point of the popular area and the surrounding region. It was beautiful from this perspective and we enjoyed the short hike with fumaroles along the way. Cost: Free Parking: Paid parking at the bottom of the hill and free parking further up the hill "

"Hverir is a top attraction in North Iceland. It is known for its bubbling pools of mud and steaming fumaroles emitting sulfuric gas. It does smell like rotten eggs, but you'll get over it pretty quickly. There is a nice wooded viewing platform you can walk along, but if you'd like to hike in the area, I linked below a 1.7 mile hike you could do here. However, note it is extremely muddy and slippery so I'd plan to wear sturdy boots and bring hiking poles. My hiking boots were pretty disgusting afterwards from the mud, but the views at the top were cool. Fun fact: NASA has used this site as a training center for their astronauts in the past! "

"Hverir stinks. Literally. This geothermal spot, just east of Mývatn, is known for its pools of bubbling mud and steaming fumaroles that emit sulfuric gas. Don't let the scent of rotten eggs stop you. The lunar-like landscape has colorful (orange, red) hills. Clearly marked paths and wooden boardwalks allow you to get close without putting yourself in danger. Though there's no cost to wander around, there's now a small fee to park. Hopefully you packed your boots."