If you're looking for a natural wonder in Iceland, I highly recommend checking out Fjaðrárgljúfur Canyon. It's not too far from the main ring road and the road to get there is in great condition. The canyon is 100m deep and 2km long, and was formed by the flow of water from glaciers over time. The river Fjaðrá runs through it, and the view is constantly changing, with a beautiful waterfall at the end. You can walk along the canyon, or down from the parking area for a different perspective. I especially recommend the hike because the view is breathtaking and the sound of the water is so calming. If you have good sturdy boots, you can also wade through the river for a unique experience. Just note that you won't be able to cross some of the waterfalls on your way back. Overall, this is a 5-star place for nature lovers and photographers, with plenty of opportunities for hiking and exploring.