Glymur is the second-highest waterfall in Iceland, with a cascade of 198 m. It was long regarded as the tallest until being surpassed by Morsárfoss, a newly measured waterfall near Morsárjökull in 2011. This amazing waterfall empties into a giant, beautiful canyon and with such a short hike, the reward is well worth the time. There are several caves along the way which are possible to to walk through and there are also various smaller waterfalls along the hike It is situated at the rear end of the Hvalfjörður.
The river Botnsá runs from the Hvalvatn lake and after a short distance the water falls down alongside the Hvalfell mountain into a steep canyon. The waterfall can be accessed from a parking area at the end of the road. Hikers can view the waterfall from marked paths on the east side of the river Botnsá.