It is truncated by two nested calderas, with the cone of Nemo Peak itself rising in the southwest end of the youngest caldera and a crater lake partially filling the northeast part, named Ozero Chernoye.

[3] These two volcanoes together have erupted about 120–130 cubic kilometres (29–31 cu mi) of tephra, covering the entire seafloor of the Sea of Okhotsk.

Two older ones reach diameters of 11 kilometres (6.8 mi) and overlap each other,[2] with an average elevation of the floor of 50–100 metres (160–330 ft).

[6] Lava flows extend down from the summit area of Nemo Peak[3] and are covered with scoria.

[11] Augite, hypersthene, labradorite, olivine and pyroxene are minerals found in Nemo lavas.

[12] Nemo Peak is one of the most active volcanoes in the Kurils and has been the site of catastrophic eruptions for 300,000 years, going back to the Pleistocene.

[13] The older Nemo calderas appear to predate the last glaciation, while the younger one is post-glacial in age.

[6] Future volcanic activity involving medium-sized or large eruptions is possible; tephra would be propagated east-northeast.

[20] Nemo Peak appears to be the source of several tephra layers found in the Sea of Okhotsk named K2 and K3.