If you're looking for a unique geological wonder, Hverfjall in Iceland is a must-visit! This 2500-year-old circular volcanic crater is one of the largest and best preserved of its kind in the world. With a diameter of 1km and a depth of 200m, it's a stunning sight. The hike to the rim is either a 10-20 min steady climb from the parking lot or a steeper climb from Dimmuborgir, but either way, it's worth it. Just make sure to wear good footwear and bring layers to protect yourself from the wind and weather changes. The rim trail offers breathtaking views and a 1h30 walk. If you don't want to tour it, the best views are 1/5 counterclockwise from the parking climb. A walking stick might be helpful, especially in winter. Enjoy the beauty of Hverfjall!