Extreme

Photo by Albertane

Caves of DrachThese four caves, with their weird formations and impressive chambers, are the most famous tourist attraction in Mallorca, Spain.
Postojna CaveThe most visited cave in Europe, and the biggest cave in Slovenia.
Cheddar CavesA group of two caves, home to the oldest complete skeleton in Britain.
Grotte de DargilanOne of the largest natural caves in France, discovered in 1880.
Aletsch GlacierThe largest glacier in the Alps, with a length of 23 kilometers and an area of 120 square kilometers.
Jostedalsbreen GlacierMeasuring more than 60 kilometers in length, this is the largest glacier in continental Europe.
Vatnajökull GlacierThe largest glacier in Iceland, covering 8% of the country's territory.
Mount VesuviusOne of the world's most dangerous volcanoes, with many people living near its crater.
Stromboli VolcanoThe volcano with the world's longest recorded period of activity: more than 2.000 years.
Mount EtnaMount Etna is one of the most active volcanoes in Europe and is Sicily’s best-known natural attraction.