Originally the above-water part of the ridge of an underwater caldera, Nishinoshima was enlarged in 1974 after eruptions created a new section of the island.

The island was merely the tip of an undersea volcano some 3,000 m (9,800 ft) in height and 30 km (19 mi) wide at the base.

2 reported to the Japan Coast Guard that, at around 11:00, white smoke rose east of the island to around 100 m (330 ft) in the air every few minutes.

The Japan Coast Guard Hydrographic Department went to observe the area using a YS-11 aircraft that same day and confirmed the presence of a cloudy vent.

[25] The new island had a 70 m (77 yd) diameter crater that frequently ejected cinders to a maximum height of 300 m (980 ft).

[citation needed] In November, a fissure eruption was noted on the new island with a chain of cinder cones running from southwest to northeast.

[27][3][28][29] By December 2013, the island rose 20–25 m (66–82 ft) above sea level, with an area of 56,000 square meters (13.8 acres).

[33] NASA says two cones have formed around the main volcanic vents and stand more than 60 m (200 ft) above sea level.

During July and August 2014, lava flow increased, causing the island to expand rapidly to the east.

[35] On 27 December 2014, Japanese authorities said the island had reached nearly 2.3 km2 (570 acres) in size and is estimated to have risen to about 110 m (360 ft) above sea level and that the volcano was still active.

[37] As of 16 September 2015, the total area of the island had decreased slightly, but the fumarolic zone had expanded as "vigorous volcanic activity continued without significant change".

Water discoloration was still evident immediately offshore in August, indicating that volcanic activity, while in significant decline, was still present.

[43] On 14 February 2017, the Japan Meteorological Agency cancelled all alerts for the island, declaring that there was no indication of subsequent eruptions.

[8] Apart from documenting the island's ecology and geology, monitoring equipment was also installed for future volcanic activity.

[53] On 6 December 2019, the Japan Coast Guard confirmed explosive activity in Nishinoshima has returned, with new lava flows entering the sea by the following day.

[5] The conditions were enough that the Meteorological Agency issued a warning to passing ships to stay clear of Nishinoshima.

[57] On 25 June 2020, the explosive-effusive eruption was still continuing, with lava flows on the northeastern slope of the volcano, as well as ash plumes reaching 2,600 m (8,530 ft).

[64] Foggy weather in Fukuoka Prefecture, Japan, and Busan, South Korea, occurred from late July to early August 2020 due to the volcanic eruption of the island.

[65] The Japan Coast Guard reported that during an overflight of Nishinoshima on 25 January 2023, an intermittent blackish-gray plumes rising 900 m (3,000 ft) from the central part of the crater was observed with brown discolored water around the island.

It is expected that organic matter, mainly deposited by nesting birds in the form of feathers or excrement, would enrich the island surface for plants to grow.

[72] To prevent interference of the colonization process, researchers were also advised not to bring external species to Nishinoshima.

In October 2016, a team of scientists visited Nishinoshima to examine its environment and geologic makeup for the first time up-close.

[8][73] Their studies have discovered that both plant and animal life continue to exist on the remaining part of the old Nishinoshima island that had not been covered by lava.

An accompanying video crew from Nippon TV captured masked boobies laying eggs and a pod of dolphins (either Indo-Pacific, Tursiops aduncus, or common bottlenose, T. truncatus) swimming off the coast.

[78] In terms of flora, plants that were present on the original island, like goosegrass and purslane, were found to be growing again on the "old" section of Nishinoshima.

[74]The island and its surrounding waters have been recognised as an Important Bird Area (IBA) by BirdLife International because it supports a population of greater crested terns.

Five species of seabirds, including brown boobies and crested terns, have also been spotted nesting on the island.

[67] During a survey flight done by an Asahi Shimbun aircraft on 3 November 2023, a white plateau of feces left by seabirds was spotted on the island.