The simple answer is that it is a glacier, a very big glacier. What is a glacier then, you ask? It’s snow, a lot of snow. Glaciers grow in winter when it is cold and snowfalls, but decrease in summer when it is hot and a lot of ice melts. Think of normal winter snow that never completely melts away. Instead, new snow falls all the time adding to the old. In the case of Vatnajökull, the snow started to add up 2500 years ago, 500 years after the Ice Age ended. Each time the added snow adds weight. This compresses the snow into a large, thick and heavy ice mass. Once the snow starts getting too heavy, it starts to very slowly slide down the mountainsides. Vatnajökull slides down Iceland’s highest peak, Hvannadalshnúkur at 2110 meter. From there it runs all the way down to the Atlantic Ocean. The weight of Vatnajökull is 3000 million tons. This immense pressure pushes the land beneath it down around 100 m. At Breiðamerkurjökull it even pushes it down 260 meters below sea level.
Apart from it being a glacier, it's also the name a National Park. Together with the former National Parks of Skaftafell and of Jökulsárgljúfur they now form Vatnajökulsþjóðgarður, Vatnajökull National Park. It’s now the largest National Park in Europe. This diverse landscape known as The Land of Fire and Ice is also home to many other natural wonders. You’ll find countless waterfalls, ice caves, ten volcanoes, geothermal areas and rivers. It’s also home to about forty glacier tongues, lagoons filled with icebergs, and plenty glacier-carved canyons. Hvannadalshnúkur Peak, Iceland’s highest and its deepest lake Jökulsárlón are also inside this park. [post:rank_math_focus_keyword] has been answered, right?