Highlights: 
The Icelandic Highlands cover the major part of the country and many of Iceland’s main natural attractions can be found there. Away from crowds, noise and bustle, the Highlands offer unique silence, serenity, peace and extreme natural beauty.
The Central Highlands
The Central Highlands cover a vast area, all at an altitude of over 500 meters, with numerous mountains reaching a height between 1000 and 2000 meters. Most of these higher mountains are covered by glaciers. Two of the highest mountains in the country (over 2000 m high) are located in Vatnajökull, namely Hvannadalshnúkur (2109 m, located in south Vatnajökull) and Bárðarbunga, a subglacial volcano in northwest Vatnajökull (2000 m).
Three of the largest glaciers in Iceland are located in the Central Highlands. These are Vatnajökull in the southeast (Europe’s largest glacier), Hofsjökull in the centre of Iceland and Langjökull, west of Hofsjökull.
Various highlands paths lie between the glaciers, open for cars around June/July. One of the major ones are Kjölur, connecting south and north Iceland (the road is located between Hofsjökull and Langjökull). Sprengisandur, is another important path, connecting south and north, and located between Hofsjökull and Vatnajökull.
Kaldidalur is a highland path stretching west of Langjökull, from Þingvellir towards the Borgarfjörður district. It then continues further north as Stórisandur.
Remember always that the natural environment that makes up Iceland's Highlands is as delicate as it is enchanting. The slightest damage inflicted upon small areas can cause erosion and irreversible landscape wounds that can easily spread over large areas. When travelling in the Highlands, therefore, visitors must at all times uphold responsible travel etiquette. Driving off roads and designated paths is strictly forbidden and punishable by heavy fines.
The South Highlands
Almost all the mountains south of the glaciers are tuff mountains. They were formed during the Ice Age, as well as the area north of Vatnajokull. Volcanic activity is confined to tuff areas of the country and in the southern Highlands are some of its most active and famous volcanoes, Hekla, Eyjafjallajökull and Katla in Mýrdalsjökull, Iceland’s fourth largest glacier.
Northeast, Central-North and Northwest Highlands
To the northeast are the Lakagígar Craters and in Vatnajökull there are Grímsvötn and Bárðarbunga along with Öræfajokull. North of Vatnajökull, the best-known volcanoes are Askja and Krafla.
The northwest and central-north Highlands consist of ancient basalt formations and it is the same for the mountains of the Eastfjords.
Highland Oases
There are a few oases in the highlands that have unique vegetation and wildlife. The most important of these are Þjórsárver, Nýidalur/Jökuldalur, Herðubreiðarlindir and Eyjabakkar. The pink-footed goose has its main nesting places at Þjórsárver and Eyjabakkar. Þjórsárver was designated as a Ramsar site in 1990. Reindeers reside in the east Highlands.
Nestled between the glaciers Eyjafjallajökull, Mýrdalsjökull, and Tindfjallajökull is Þórsmörk (Thor's Valley), a nature reserve in the southern Icelandic highlands. Þórsmörk is one of Iceland's most popular hiking destinations.
Strictly speaking, Þórsmörk is a valley and a mountain range between the Krossá, Þröngá, and Markarfljót rivers. Locals, however, often use the name "Þórsmörk" when referring to a much larger region that is composed of the area between Þórsmörk proper, and the Eyjafjallajökull glacier volcano.
Landscapes and Geology
Contrasting vistas of lush oases and roaring glacier rivers cutting through black desert expanses not only make Þórsmörk unique to Iceland but to the entire world. Parts of the valley are rich with moss, fern, and Birchwood, while jagged mountain ridges and ice-capped peaks crown the horizon.
The valley's climate is warmer and calmer than usual in south Iceland, which often causes Þórsmörk's mountains to be cloaked in a veil of mist that materialises when the warm valley air ascends and mixes with the descending cold breath of the glaciers above.
Activities
Þórsmörk's surrounding hills, slopes and mountains are beset with small valleys and gullies that make for some of Iceland's most astonishing hiking routes. Experienced hikers, therefore, have a wealth of trails to trek, varying in distances and difficulty. In fact, Þórsmörk offers two of the most popular trails in Iceland, the Fimmvörðuháls and the Laugavegur.
Fimmvörðuháls is a 30km trail that takes you into the hills beneath the Eyjafjallajökull glacier volcano and to the volcanic craters Magni and Móði, which are still steaming from the eruption of 2010. The 55 km Laugavegur path takes you from Þórsmörk to the Landmannalaugar geothermal area which is home to an incredible wealth of hot springs and rhyolite mountains of vibrant colours. A short but demanding hike from Þórsmörk up Mt.Útigönguhöfði is suitable for those who are looking for stunning views and don't mind a little physical challenge.
Accommodation and How to get there
During winter (October 16th - April 30th) the road into Þórsmörk is impassable. In summer (May 1st - October 15th) a special 4x4 mountain bus runs three times per day from the BSÍ bus terminal in central Reykjavík. Once there you have the choice setting up base in a small hut in Húsadalur valley, a private room or a dormitory in Langidalur valley, or to camp in Þórsmörk's campsite. Please note that the huts, private rooms and dormitories must be booked well in advance.
The glacier volcano of Eyjafjallajokull (1651 m) is located at the borders of the South Icelandic highlands. It featured prominently in world news in 2010 when ash from its eruption halted air traffic in Europe.
An ice cap of about 100 km with several outlet glaciers covers the caldera of Eyjafjallajökull that stands at the height of 1651 meters. The diamaeter of its highest crater is around 3-4 km2 wide and the rim has several peaks.
Eyjafjallajokull glacier volcano lies north of Skogar, and to the west of Myrdalsjokull glacier and the massive volcano there; Katla.
Eyjafjallajokull is thought to be related geologically to Katla in Myrdalsjokull and eruptions in the former have often been followed by eruptions in the latter.
The 2010 eruptions
The end of 2010 saw some small seismic activity that gradually increased and resulted in a small eruption in March of 2010, characterized by a flow of alkani-olivine basalt lava.
This first stage lasted until April 12th and created the volcanic craters Magni and Modi at the Fimmvorduhals trail. They are so far Iceland's newest vocanic craters, and still eminate steam with lava glowing under the surface.
However it was the second phase of the eruption that started on April 14th that created the huge ash cloud that rose about 9 km into the skies.
This eruption halted air traffic in Europe for days, and its estimated that as many as 107.000 flights may have been cancelled during the week it lasted.
The ejected tephra measured around 250 million cubic meters. This ash cloud lasted for six days and some more localized disruption continued into May. The eruption was officially declared to be over in October 2010, as the snow on the glacier had ceased to melt.
Future volcanic developments?
Eyjafjallajokull erupted in years 920, 1612 and again 1821-1823.
Its latest eruptions were the two that occurred in 2010.
Future volcanic developments remain unclear. The area is still highly active and can be quite unpredictable. It continues, however, to be closely monitored by The Icelandic Meterological Office.
Gigjokull is one of two glacier outlets from the glacier volcano Eyjafjallajokull, the other being Steinholtsjokull.
The 2010 Eyjafjallajokull eruption was close to the head of Gigjokull. Gigjokull empties out of the summit crater area at 1600 meters (5249 feet), flows across the ice cap to 1500 meters (4921 feet) and then descends in an icefall down 200 meters (656 ft). Water flowing from Gigjokull enters the Markarfljot river and eruptions in the area have caused great glacier bursts, 2010 being the latest example.
