Gullfoss ("Golden Falls") is a waterfall on the glacier-fed Hvítá river in south-west Iceland, on the boundary between the municipalities of Bláskógabyggð and Hrunamannahreppur. The river drops in two stages, of 11 m (36 ft) and 21 m (69 ft), into a crevice 32 m (105 ft) deep, about 20 m wide and 2.5 km long that runs at right angles to the flow. Its volume swings with the seasons, from an average of about 80 m³/s in winter to about 141 m³/s in summer, and the largest flood measured there reached 2,000 m³/s. Saved from hydroelectric development in the early 20th century and protected as a permanent conservation site since 1979, it is one of the three main stops on the Golden Circle tourist route.
Because almost all of that water starts as ice on Langjökull, Iceland's second-largest ice cap, the clearest way to understand Gullfoss is through its year: the frozen low-water months, the thaw in the highlands, the summer melt peak, and the autumn run of the river down to the sea.
Winter at Gullfoss: 80 m³/s Beneath Ice on the Hvítá
From late autumn to early spring, Gullfoss carries its smallest flow, on average about 80 m³/s, little more than half its summer volume. Up on Langjökull, the 870 km² ice cap that feeds the river, snow builds up instead of melting. With less water arriving, the falls shrink and spray freezes onto the canyon walls, coating the ledges of the "staircase" above the main drop in ice. A winter view of the falls became the cover of Echo & the Bunnymen's 1983 album Porcupine.
Low water does not mean a quiet river. The Hvítá has a reputation as Iceland's most dangerous river because of its floods, and those floods are worst in winter. Light is short too. At 64° north, Reykjavík gets less than five hours of daylight between 2 December and 10 January, with the sun no more than 3° above the horizon, and the falls, inland at a similar latitude, see the same short days. By the end of January, daylight in Reykjavík has stretched back to about seven hours.
Winter is also when the highland roads that lead toward the river's source are shut. The Kjölur track (F35), which runs between Langjökull and Hofsjökull, and the Kaldidalur road (550) on the glacier's west side open only in the summer months, and the one bridge across the Hvítá near its source is open only in summer.
The Thaw on Langjökull and Hvítárvatn
As temperatures rise in late spring, the source of Gullfoss comes back to life. The Hvítá begins at Hvítárvatn, a 30 km² lake at 420 m above sea level, 45 km north-east of the falls and up to 84 m deep. About two-thirds of the lake's water appears to come from Langjökull through underwater channels rather than surface streams, and the glacier's outlet tongues, Norðurjökull and Suðurjökull, used to reach the lake itself. They did so until about 1900, and have since retreated rapidly.
Langjökull is about 50 km long and 15–20 km wide, holds about 195 km³ of ice up to 580 m thick, and rises to about 1,450 m at Baldjökull, its northern summit. Its largest recorded extent was in 1840. Some researchers think that at recent rates of warming it could disappear within about 150 years, which would remove the source of the summer melt that sets the rhythm of the falls.
The name Hvítá, "white river", comes from the silt that glacial melt carries; the same adjective turns up across Iceland because most of the country's fresh water starts as glacier ice. From Hvítárvatn the river flows about 40 km south across the highlands before reaching the falls. About a kilometre above Gullfoss it turns sharply west, spreads over a wide, curved three-step staircase, and then plunges in its two stages into the crevice.
The ground around the source is volcanic. Langjökull covers the higher parts of a volcanic system, and the Kjalhraun lava field, part of which is about 7,800 years old, spreads east of the glacier toward the Hveravellir geothermal field. With 32 eruptions in the last 10,000 years, the system is quiet by Icelandic standards. The mountains on the glacier's eastern edge frame the lake: Skriðufell, 1,235 m, rises directly above Hvítárvatn, and the Jarlhettur ("the earl's hat") are a ridge of palagonite peaks that formed in a fissure eruption beneath the ice during the Ice Age. The travellers Eggert Ólafsson and Bjarni Pálsson gave the oldest description of the Hveravellir hot springs in 1752.
Langjökull feeds more than one river, and the shared name confuses visitors. Its western meltwater runs into a second, unrelated Hvítá that reaches the sea in Borgarfjörður, west of the ice cap. On that side, water passes under the Hallmundarhraun lava field, erupted about 1,000 years ago, and emerges as the springs of Hraunfossar near Húsafell. The Hvítá of Gullfoss is the southern one, sometimes distinguished as Hvítá in Árnessýsla after the old county it crosses.
Summer Peak at Gullfoss: 141 m³/s and the Sigríður Tómasdóttir Story
From June to August, melt on Langjökull pushes the average flow at the falls to about 141 m³/s. This is the season of long light, when Reykjavík's sun barely sets between 20 May and 24 July, and of the biggest crowds. Iceland receives most of its tourists in June, July and August; in 2014 about 42 percent of visitors came in those three months, and by 2025 the country was receiving just under 2.3 million foreign overnight visitors a year, with tourism worth 8.8 percent of GDP. Most of them see Gullfoss on the Golden Circle, a loop of about 300 km from Reykjavík that also takes in Þingvellir National Park and the Haukadalur geothermal area, where Strokkur erupts every 5–10 minutes and Geysir, the spring that gave the English word geyser its name, now erupts only rarely. Many tours add the Kerið volcanic crater, Skálholt cathedral, the town of Hveragerði or the Nesjavellir and Hellisheiði geothermal power plants. Organised rafting trips also run on parts of the Hvítá.
The falls were nearly lost to a summer-flow economy of another kind. In 1907 landowners including Tómas Tómasson of Brattholt farm signed a deal allowing a hydroelectric dam across the Hvítá that would have drowned Gullfoss. His daughter, Sigríður Tómasdóttir (1871–1957), who had grown up guiding visitors to the falls with her sisters, fought it: she took legal action, staged protests, made repeated trips of about 120 km to Reykjavík, by some accounts on foot, and reportedly threatened to throw herself into the falls. Her lawyer, Sveinn Björnsson, later became Iceland's first president.
Her case failed in the courts, but it won public support. The foreign investors who had leased the falls through the owners never raised enough money, the leases were cancelled, and the dam was never built. The land was later sold to the Icelandic government, which made Gullfoss a permanent conservation site in 1979. She is often described as Iceland's first environmentalist, and she is buried in the cemetery at Haukadalur, the valley of Geysir on the same tourist loop.
Autumn Downstream: Tungufljót, Brúará and the Ölfusá to the Atlantic
As the melt season ends in autumn, flows at the falls fall back toward their winter level, but the river below Gullfoss keeps growing. Leaving the 2.5 km crevice, the Hvítá runs south between the districts of Biskupstungur and Hrunamannahreppur, where three tributaries, the Tungufljót, the Brúará and the Stóra-Laxá, join it and roughly double its volume. It then crosses the flat farmland near Grímsnes and passes behind the mountain Ingólfsfjall. Three of its four bridges are in these lowlands.
Just north of the town of Selfoss, the Hvítá meets the Sog, which drains Þingvallavatn through the lakes Úlfljótsvatn and Álftavatn over a 21.9 km course with an average flow of about 110 m³/s, and the two become the Ölfusá. The Sog shows what Sigríður's campaign prevented on the Hvítá: it carries three hydroelectric stations, Ljósafossstöð (15 MW), Írafossstöð (48 MW) and Steingrímsstöð (27 MW). Langjökull reaches this point too: research shows that large amounts of its meltwater travel underground to springs around Þingvallavatn, about 50 km south of the glacier. The Ölfusá runs only about 25 km to the Atlantic, yet it is Iceland's largest river by volume, with a mean discharge of 423 m³/s and a drainage basin of 5,760 km². It supports a large salmon fishery, and the Flói Nature Reserve lies along its eastern bank near the mouth.
The record 2,000 m³/s flood at Gullfoss was about 14 times the summer mean, a reminder that seasonal averages hide the river's sudden surges. When the highland roads close again and the glacier stops melting, the falls drop back toward their winter flow and the cycle starts again.
The geothermal stop a few kilometres from the falls is covered in our guide to Geysir and the Haukadalur valley, the country's larger ice cap in the article on Vatnajökull, and the light, weather and road openings that frame a visit to Gullfoss in our overview of the seasons in Iceland.