Summary: Gluggafoss (also called Merkjárfoss) is an interesting waterfall, where the Merkjá River has carved a channel and three natural arches through a hill.

Gluggafoss is the official name of this waterfall, with “glugga” being the Icelandic term for “window” (referring to the windows in the bedrock). It’s also recognised as Merkjárfoss. Gluggafoss is the most prominent of a series of waterfalls on the Merkjá River in southern Iceland, which drains the meltwater from the Tindfjallajokull glacier. The river has carved a channel through a hill, first dropping 44m into a narrow recess, and then spreading out over a broader ledge and falling 8.5m across three main channels.

Gluggafoss waterfall

The upper falls have carved three natural arches through the stratified palagonite or tuff (heavily compacted ash, sand, and boulders). This is part of the distinctive Gluggafoss geology of holes, arches and tunnels. The first arch is situated near the top of the falls and is difficult to see from its base, while the other two are found one on top of the other near the base of the upper tier.


Prior to 1947 the upper half of the falls was not visible, as the water had eroded the channel back into the grotto. The only portion of the falls that could be seen was what was visible between the arches or “windows”. Following the eruption of the volcano Hekla in 1947, over 20cm of ash was deposited in the drainage above the falls, which washed downstream and clogged the tunnel. After about 50 years, this debris from by the eruption was washed away, restoring Gluggafoss to its previous form. 

Getting to Gluggafoss

There is a small parking area just off Route 261 (17.3km east of Hvolsvöllur). You can see the falls from the carpark, and a path goes to the base of the lower falls (you can go behind the waterfall) and up to the base of the upper falls.

IMG 1720 LRP 2 Gluggafoss - a Waterfall with a Window

More information

This was one of the many waterfalls (and countless other natural attractions) on our week-long Circuit around Iceland.

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