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Þríhyrningur mountain hike

South IcelandMountainFree entrySummer hike
ÞRÍHYRNINGUR IN SHORT

Þríhyrningur ("three-peaks") is a distinctive three-peaked mountain above Fljótshlíð in South Iceland, 678 m high and about 120 km from Reykjavík. It is free to visit, best hiked in summer, and the round trip of about 7 km takes around 3 hours.

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Quick factsHistoryGetting thereThe hikeAroundBest time to visitSafety tipsFacilitiesMapNearbyWhere to stayFAQ

About Þríhyrningur

Þríhyrningur rises on its own north of the farmland of Fljótshlíð, its three summits visible from much of South Iceland. Between the peaks lies Flosadalur, a small valley named after Flosi of Svínafell, a character in Njáls saga, one of Iceland's best-known medieval sagas.

The mountain is 678 metres high. According to local accounts it was formed long ago, when the land lay under ice-age glaciers. Two gorges, Katrínargil and Tómagil, cut into its sides.

The hike up is steep in places but doesn't require technical skill in summer conditions, and the reward from the top is one of the better viewpoints in the region: Hekla to the north, Eyjafjallajökull and the Fljótshlíð slopes to the south-east, the Tindfjöll mountains and Þórsmörk to the east, and on a clear day the Vestmannaeyjar islands out to sea.

It is a quiet hike, a long way from city traffic and well off the usual tourist route, and for many people that is the reason to come.

Quick facts

Height678 m
RegionSouth Iceland, north of Fljótshlíð
From ReykjavíkAbout 120 km, around 1 hour 45 minutes by car
From HvolsvöllurAbout 18 km
TrailheadBy the Fiská river in Vatnsdalur, reached via Route 261 and Tumastaðir
EntryFree
Hike lengthAbout 7 km and 3 hours round trip
ClimbAbout 500 m of ascent
DifficultyModerate; short but steep, on sheep tracks rather than a built path
SeasonBest from May to October; the access road can be closed by snow in winter

A mountain from the sagas

Flosadalur, the valley between Þríhyrningur's peaks, takes its name from Flosi Þórðarson of Svínafell, one of the central figures in Njáls saga, who is said to have hidden here with his men after the burning of Njáll's farm at nearby Bergþórshvoll. The story is one of the most dramatic in the saga, and the landscape around Fljótshlíð is full of place names tied to it.

A local legend adds that Flosi hid a chest of treasure in a cave on the north side of the mountain. Nobody has found it.

Whether or not every detail of the saga is historically accurate, the mountain has clearly been a landmark for the farms of Fljótshlíð for as long as they have existed, visible from almost every farmstead in the valley below. An old travel route through the district, no longer in use, passed close by.

How to get to Þríhyrningur

By carFrom Reykjavík, take Route 1 south-east through Hveragerði and Selfoss to Hvolsvöllur. From there follow Fljótshlíðarvegur (Route 261) and turn left at the Tumastaðir forestry station. Drive through Tumastaðir and the Tunguskógur forest into the Vatnsdalur valley for about 7 km, until you reach the Fiská river and the parking area.
Hiking thereThe trail starts close to the parking area at Fiská and climbs steeply towards the peaks. Allow around 3 hours for the round trip and expect a proper climb, not a gentle walk.
By public transportThere is no public transport to the trailhead. A rental car is the practical way to reach it.

The unpaved approach road can be affected by snow and is generally best driven from late spring to autumn.

The hike up Þríhyrningur

The route is about 7 km there and back, with roughly 500 metres of climbing. Most hikers take around 3 hours, a little less if they are fit and a little more with photo stops.

Start: the Fiská riverPark by the river in Vatnsdalur. The route heads up from Fiská towards the south-west, onto a small plateau on the south-east side of the mountain.
The climbFrom the plateau the slope steepens. There is no built path. You follow sheep tracks over grass, gravel and loose rock, so take your time and watch your footing.
Flosadalur and the three peaksHigher up you come to Flosadalur, the hollow between the three peaks. From here you can reach the tops and see how the mountain got its name.
The viewEach peak gives a slightly different view: Hekla to the north, Tindfjöll and Þórsmörk to the east, Eyjafjallajökull to the south-east, and Seljalandsfoss, the south coast and Vestmannaeyjar to the south.
The way downReturn the same way. The steep sections are harder going down than up, especially when wet, so keep some energy for the descent.
Vatnsdalshellir caveA cave in Vatnsdalur, near the start of the route, can be added to the outing if you have time.

The route follows sheep tracks rather than a built, signed path, and cloud can settle on the peaks quickly. Carry a map or a GPS track, and turn back if you lose visibility.

Places to explore around Þríhyrningur

The mountain is in Njáls saga country, and there is plenty to fill the rest of the day nearby.

FljótshlíðA green farming district and one of the main settings of Njáls saga, with active volcanoes on three sides: Hekla to the north, Katla to the east and Eyjafjallajökull to the south. There is accommodation and services along the road.
NauthúsagilA narrow ravine below Eyjafjallajökull, known for the wild rowan tree growing along its rim. You walk and wade up the stream to a waterfall, and the rocks are slippery in places.
Seljalandsfoss and GljúfrabúiSeljalandsfoss drops about 60 metres right beside the Ring Road, and you can walk behind it. Gljúfrabúi is hidden in a cleft in the cliff a short walk away.
StakkholtsgjáA canyon about 100 metres deep and 2 km long on the way into Þórsmörk, with several streams running through it and a waterfall at the far end. The road to it is a highland road with river crossings, so go with a suitable vehicle or on a tour.
HvolsvöllurThe nearest town, with shops, fuel and places to eat.

Best time to visit Þríhyrningur

SummerThe main hiking season, roughly May to October, with the access road and trail clear and long daylight to enjoy the views.
WinterSnow and ice make both the approach road and the climb itself hazardous, and the road can be closed by heavy snow. Not recommended without local knowledge and proper equipment.

Safety and practical tips

  • Wear proper hiking boots, the trail is steep and can be loose underfoot.
  • Bring layers, weather changes quickly at altitude even in summer.
  • Check the forecast for the area before setting out, the peaks catch wind and cloud that the valley below doesn't see.
  • Start early in the day to leave a safety margin for the descent.
  • Carry water and food; there is nothing at the trailhead.
  • Pick a clear day if you can. The view is the reward, and it disappears in low cloud.

Facilities and accessibility

None at the trailhead. The nearest services are in Hvolsvöllur.

On the map

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Nearby places worth a stop

HeklaHeklaVisible from the summitKeldurKeldurHistoric turf farm nearbyGluggafossGluggafossWaterfall in Fljótshlíð with windows worn through the rockNauthúsagilNauthúsagilNarrow ravine with a rowan tree and a waterfallSeljalandsfossSeljalandsfossWaterfall you can walk behindGljúfrabúiGljúfrabúiWaterfall hidden in a cleft next to SeljalandsfossStakkholtsgjáStakkholtsgjáDeep canyon on the way into Þórsmörk
ÞórsmörkNature reserve visible from the peaks

Where to stay near Þríhyrningur

Hvolsvöllur and the wider Fljótshlíð area have hotels, guesthouses, hostels and farm accommodation within easy reach of the trailhead.

Þríhyrningur FAQ

How hard is the hike up Þríhyrningur?

It is a steep climb in places, about 7 km and 3 hours round trip with around 500 metres of ascent. It suits hikers with reasonable fitness rather than complete beginners.

How far is it from Reykjavík?

About 120 km, around 1 hour 45 minutes by car to the trailhead.

Where does the hike start?

At the parking area by the Fiská river in Vatnsdalur, about 7 km beyond Tumastaðir on the Fljótshlíð road (Route 261).

Is there a fee to hike here?

No, there is no entrance fee.

What can I see from the top?

On a clear day, Hekla, Tindfjöll, Þórsmörk, Eyjafjallajökull, Seljalandsfoss and the Vestmannaeyjar islands.

Can I hike Þríhyrningur in winter?

It is not recommended. The road can be closed by snow and the steep slopes are icy. The usual season is May to October.

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