It is, just after the Pasterze Glacier and Gepatschferner, the third largest and by volume (1.2 km3) the most massive glacier in the eastern alps. The Morteratsch Glacier is a typical valley glacier with a pronounced ice front. The accumulation zone lies between the peaks of Piz Morteratsch, Piz Bernina, Crast' Agüzza, Piz Argient, Piz Zupò and Bellavista. From Piz Argient to the ice front in the Val Morteratsch, its horizontal extent is about ~7 km (4.3 mi), with an altitude difference of up to 2,000 m (6,600 ft). Together with the Pers Glacier, originating at Piz Palü, which joins the Morteratsch just below the rock formation Isla Persa ("Lost Isle"), it covers an area of about 16 km2 (6.2 sq mi). The volume of the ice is estimated to be about 1.2 km3. The Morteratsch Glacier drains through Inn River and Danube into the Black Sea.