Mount Berlin is a glacier-covered volcano in Marie Byrd Land, Antarctica, 100 kilometres (62 mi) from the Amundsen Sea. It is a roughly 20-kilometre-wide (12 mi) mountain with parasitic vents that consists of two coalesced volcanoes: Berlin proper with the 2-kilometre-wide (1.2 mi) Berlin Crater and Merrem Peak with a 2.5-by-1-kilometre-wide (1.55 mi × 0.62 mi) crater, 3.5 kilometres (2.2 mi) away from Berlin. The summit of the volcano is 3,478 metres (11,411 ft) above sea level. It has a volume of 200 cubic kilometres (48 cu mi) and rises from the West Antarctic Ice Sheet. It is part of the Marie Byrd Land Volcanic Province. Trachyte is the dominant volcanic rock and occurs in the form of lava flows and pyroclastic rocks.

The volcano began erupting during the Pliocene and was active into the late Pleistocene and the Holocene. Several tephra layers encountered in ice cores all over Antarctica – but in particular at Mount Moulton – have been linked to Mount Berlin, which is the most important source of such tephras in the region. The tephra layers were formed by explosive eruptions that generated high eruption columns. Presently, fumarolic activity occurs at Mount Berlin and forms ice towers from freezing steam.

Mount Berlin lies in Marie Byrd Land, West Antarctica, 100 kilometres (62 mi) inland from the Hobbs Coast of the Amundsen Sea. The volcano was studied during field trips in December 1940, November 1967, November–December 1977 and 1994–1995. It is named after Leonard M. Berlin, who led the 1940 research visit to the mountain.

Mount Berlin reaches a height of 3,478 metres (11,411 ft) above sea level, making it the highest volcano in the Flood Range. It is the western end of the range; Wells Saddle separates it from Mount Moulton volcano farther east. Mount Berlin's peak is 2.1 kilometres (1.3 mi) above the highest local elevation of the West Antarctic Ice Sheet. The summit crater (Berlin Crater) is 2 kilometres (1.2 mi) wide and has sharply defined, ice-crowned edges; the highest point of the volcano is on the southeastern margin. Mount Berlin consists of two overlapping edifices: Mount Berlin proper and Merrem Peak 3.5 kilometres (2.2 mi) west-northwest. Merrem Peak is about 3,000 metres (9,800 ft) high and has a 2.5-by-1-kilometre-wide (1.55 mi × 0.62 mi) crater at its summit. These craters are aligned east–west, like other Flood Range calderas. Mount Berlin has variously been described as a composite volcano, shield volcano or stratovolcano with a volume of about 200 cubic kilometres (48 cu mi). The entire combined edifice has a length of about 20 kilometres (12 mi). Its slopes have inclinations of about 12–13°.

The volcano is covered by glaciers, resulting in only a few rocky outcrops being visible on the mountain. Despite this, the volcano is considered to be well-exposed in comparison to other volcanoes in the region. Monogenetic volcanoes on the northern flank of Mount Berlin have generated two outcrops of mafic lava and scoria, one of which is found at Mefford Knoll on a linear vent. On the southeastern flank, a fiamme-rich ignimbrite crops out and is correlated to a flank vent on the northeastern flank. A ridge extends northwestward from Merrem Peak; at its foot is Brandenberger Bluff, a 300-metre-high (980 ft) outcrop of lava and tuff. This structure formed phreatomagmatically; it was formerly interpreted as a subglacial hyaloclastite. Other topographical locations on Mount Berlin are Fields Peak on the northern flank, Kraut Rocks at the west-southwestern foot, Walts Cliff on the northeastern flank and Wedemeyer Rocks at the southern foot. The existence of tuyas has been reported from Mount Berlin. According to a 1972 report, tephra overlies ice at some sites. Nonvolcanic features include incipient cirques on the northern and western side.

The Marie Byrd Land Volcanic Province features 18 central volcanoes and accompanying parasitic vents, which form islands off the coast or nunataks in the ice. Many of these volcanoes form distinct volcanic chains, such as the Executive Committee Range where volcanic activity has shifted westward at a rate of about 1 centimetre per year (0.4 in/year). Such a movement is also apparent in the Flood Range, where activity migrated from Mount Moulton to Mount Berlin. This movement appears to reflect the propagation of crustal fractures, as plate motion is extremely slow in the region. Volcanic activity appears to take place in three phases, an early mafic phase, often followed by a second felsic phase. End-stage volcanism occurs in the form of small cone-forming eruptions. Ignimbrites are rare in Marie Byrd Land; the outcrop on the southeastern flank of Mount Berlin is an uncommon exception.

Activity in the Marie Byrd Land Volcanic Province began during the middle Miocene and continued into the later Quaternary; argon-argon dating yielded ages as young as 8,200 years. Four volcanoes in the Marie Byrd Land Volcanic Province – Mount Berlin, Mount Siple, Mount Takahe and Mount Waesche – were classified as "possibly or potentially active" in the 1990 Antarctic Research Series by LeMasurier et al., and active subglacial volcanoes have been identified on the basis of aerophysical surveys.

The volcanic province is related to the West Antarctic Rift which is interpreted as a rift or as a plate boundary. The West Antarctic Rift has been volcanically and tectonically active over the past 30–25 million years. The basement crops out near the coast and consists of Paleozoic rocks with intruded Cretaceous and Devonian granites which were flattened by erosion, leaving a Cretaceous erosion surface on which volcanoes rest. The volcanic activity at Mount Berlin may ultimately relate to the presence of a mantle plume that is impinging onto the crust in Marie Byrd Land.