Mount Michael has a lava lake in its summit crater, which is fumarolically active, and there is widespread evidence of recent eruptions across the island.

The island is used as a breeding ground by many bird species, including penguins, but is barren of vegetation apart from lichens and some moss-covered patches.

[4] The islands are very remote and thus volcanic eruptions tend to go unnoticed,[5] and bad weather and hazardous oceanic conditions make landings difficult.

[7] During the past five million years, this subduction process has given rise to the South Sandwich volcanic arc.

On the eastern side of the island, 6 kilometres (3.7 mi) wide Cordelia Bay opens to the northeast between Nattriss Point[a],[13][14] a rocky headland,[12] to the east and Sombre Point to the north, with the Brothers Rocks 2 kilometres (1.2 mi) due north of Cordelia Bay[13][14] and reefs especially on its northern side.

Between these lies the ice-covered bulk of the island with the 990 metres (3,250 ft) high Mount Michael volcano.

[19] Rocky outcrops occur at the coasts, eroded pyroclastic cones on the eastern side and the Mount Michael volcano.

[1] A glacier descends on Mount Michael's eastern side, and the ice is full of crevasses.

[14] There are four craters;[18] the southern one has been partially eroded away[27] and river erosion in the Ashen Hills has formed gullies[17] that expose deposits from base surges.

[32][29] Saunders Island reaches a width of 55 kilometres (34 mi) at 2,500 metres (8,200 ft) depth,[33] and several submerged ridges extend from it.

[40] Pahoehoe and aa lava flows were recently emplaced on the northern sector of the island,[41] surrounding the former shore cliffs[34] and sea stacks that constitute the Yellowstone Crags,[42] and forming the Blackstone Plain and Ollivant Point; they may have been erupted from the northern flank in the late 19th/early 20th century.

Dark coloured layers of volcanic ash are embedded within the ice, presumably from explosive eruptions.

[35] Remote sensing has identified a lava lake in the summit crater of Mount Michael[21] with a surface area of about 0.01 square kilometres (0.0039 sq mi).

[51] Numerous fish species have been recorded in the waters off Saunders, as well as cephalopods, crustaceans and holothurians.

Antarctic terns, king penguins and southern giant petrels visit the island, but without evidence of breeding.

[55] Penguin colonies occur mostly in the ice-free coastal areas, such as the Ashen Hills and Blackstone Plain.