The Aletsch Glacier () or Great Aletsch Glacier () is the largest glacier in the Alps. It has a length of about (2014), has about a volume of (2011), and covers about (2011) in the eastern Bernese Alps in the Swiss canton of Valais. The Aletsch Glacier is composed of four smaller glaciers converging at Concordia Place, where its thickness was measured by the ETH to be still near . It then continues towards the valley before giving birth to the Massa. The Aletsch Glacier is – like most glaciers in the world today – a retreating glacier. As of 2016, since 1980 it lost of its length, since 1870 , and lost also more than of its thickness.