2. Þórsmörk

The nature in Þórsmörk (Thorsmork) is very beautiful. On the way there you have to cross some rather big rivers so it is recommended to go there by bus. The glaciers seems to come crawling down, there are some green areas, mountains in various sizes and the rivers, all helping to make this spot beautiful.
Check this page to get more information about trips to Þórsmörk and the place itself.
About 2-3 hours drive from Reykjavik.