Bláhnjúkur (Blue Mountain in English) is in the beautiful “Landmannalaugar” area. It’s very easy to hike to the top with a very obvious track all the way. The view from Bláhnjúkur is stunning, 360-degree view over the very colorful Landmannalaugar.
The track down Bláhnjúkur is one of the best mountain bike rides in Iceland. Beware though: there are usually a lot of people hiking up there so it probably better to go in the evening to get a good ride down. There are three routes down the mountain, each one better than the next.