Going into Landmannalaugar is one of the most unique drives you can do in Iceland. Along the way are water filled craters, lava fields and epic waterfalls. After you cross the final river you make it to Landmannalaugar a sanctuary deep in the highlands. From here you can go on many hikes into the orange mountains or just soak in the hot spring.
A great way to explore all the best spots is to join a day trip from Reykjavik in a super jeep. Your guide will take you to the best locations and you don't need to worry about renting a 4x4 car.