The glaciers and ice caps of Iceland cover 11.1% of the land area of the country (about 11,400 km² out of the total area of 103,125 km²) and have a considerable impact on its landscape and meteorology. An ice cap is a mass of glacial ice. Nowadays glaciers are also contributing to the Icelandic economy, with tourists flocking to the country to see glaciers on snowmobiles and on glacier hiking tours. 
Iceland is losing ice due to climate change. The glacier “Okjökull” glacier in West Iceland has lost its glacier title and is now simply known as “Ok”. In order to fit the criteria glaciers need to be thick enough to sink and move under their own weight, which Ok is not. Ok is the first Icelandic glacier to lose its title
In Iceland we count 13 glaciers, the smallest one Snæfellsjökull covering an area of about 11 square kilo meters and the largest one covering up to 8.300 square kilo meters, Vatnajökull glacier, Europe´s largest glacier and one of the largest plateau icecap in the world. 
Glaciers form where mean annual temperatures are below 0°C, and where snow and winter surpasses summer melt. Mean annual temperatures in the coastal areas around Iceland lie everywhere well above 0°C, but temperatures are generally below that in areas above 600-700 MASL. This means that glaciers are located in highlands and mountainous areas.
The glacier Vatnajökull began formation 2.500 years ago but three thousand years ago the Ice Age glacier had disappeared altogether. During the ice age however, most of Iceland was covered by a large glacier ice cap. Average thickness of Vatnajökull glacier is around 450 m, the thickest about 900 m and below the glacier there are few active central volcanoes.
The size of the glaciers has got to do with the climate. In warmer periods the glaciers retreat and during cold periods the glaciers advance, surge and form glacier outlets. Glacier outlets form because of the weight of the ice. When the weight becomes too heavy the glacier advances, calves and can reach all the way to the shore.
Glacial rivers are formed due to melting of the ice because of volcanic and geothermal activity underneath the glaciers. When volcanic activity occurs under the glacier, the resulting meltwater can lead to a sudden glacial outburst flood, known in Icelandic as jökulhlaup. 
A glacier outburst flood can happen when water gets trapped underneath the ice and the geothermal and volcanic activity continues to melt the ice until the barriers brake and causes flooding. These rivers flow for many years and carry with them mud, sand and rocks that are then all that is left when the rivers dry up or start flowing in another direction, leaving nothing behind but black desert sands.