[12] Most of the inside of the island is covered with heavily crevassed ice,[8] which reaches thicknesses of 80 metres (260 ft) and extends to the coast.

[9] The 1,209 metres (3,967 ft)[13] high Mount Hodson rises on the western side of the island[10] and has a flat summit.

[8] It features a 900 metres (3,000 ft) wide summit crater[14] surrounded by two concentric sector collapse scars.

[19] Finger Point appears to consist of a lava flow with preserved surface features that extends northwards from the scree-covered slopes of Visokoi, forming a low-lying coastal platform.

The total volume of Visokoi complete with the submarine parts is about 3,000 cubic kilometres (720 cu mi)[21] and consists mostly of pillow lavas.

[32] The island grew during the past one million years by an alternation of pyroclastic rocks[8] and lava flows with columnar jointing,[33] cut by dykes,[34] building one volcano.

[35] Later the eastern cinder cones formed, and the western side of the island was subject to coastal erosion.

[38] The occurrence of historical eruptions is uncertain,[12] but differences between the appearance of the island reported in 1819 and 1830 imply that one caldera formed between 1819 and 1830, probably in 1829,[39] while a sector collapse took place between 1927 and 1930.

[40] Non-vertebrates include mites and springtails[35] while amphipods,[44] brittle stars, bryozoans, sponges[45] and hydrozoans have been recovered from the shallow water surrounding Visokoi.

[48] Almost a thousand Antarctic fur seals were seen at Irving Point in 1964, making it the largest occurrence in the South Sandwich Islands.

[49] Visokoi and the northern South Sandwich Islands were[50] discovered on the 23 December 1819 by the Thaddeus von Bellingshausen expedition.