A solitary sliver of land rose from the Caspian Sea near Azerbaijan, and it vanished almost as swiftly.

This island, known as Kumani Bank or Chigil-Deniz, did not exist on any maps in 2022. Yet it emerged in early 2023. Its brief life fascinated local experts and surprised onlookers, Science Alert reports.

It now sits underwater once more.

Photo: Pexels

An island materialized in the Caspian Sea, then vanished.

The Mud Volcano Beneath

Kumani Bank rises from a mud volcano about 20 kilometers from Azerbaijan’s mainland. The feature stretches under the surface and sometimes bursts through the water.

Officials call this sudden mound a “ghost island.” Satellite images recorded its formation in early 2023, NASA’s Earth Observatory notes.

Past activity at Kumani Bank often involved fiery jets. In some cases, tall columns of flame shot hundreds of meters high. The 2023 outburst, however, produced no verified fire. The land simply crept above the waves, NDTV reports. It reached about 400 meters across. The resulting peak showed up quickly and started to erode soon afterward.

Photo: Pexels

It formed from a mud volcano eruption beneath the waves.

A Flicker of Land

NASA’s Landsat 8 and 9 images documented the island’s appearance. One picture from February 2023 displayed a mound surrounded by a plume of sediment. By December 2024, only a tiny spot poked out above sea level, Space.com reports. Then it slipped away.

This sea-based mud volcano erupted at least eight times before. One event in 1861 generated an islet barely 87 meters wide. It persisted for only about a year. Another blast in 1950 formed a landmass 700 meters across and six meters above the water. That version gradually slipped beneath the Caspian.

Expert Observations

Azerbaijan has an unusual concentration of mud volcanoes. More than 300 of these volatile features dot the country’s interior and appear offshore in the Caspian Sea. Their eruptions expel mud, gas, and sometimes flames over a short interval. According to Popular Mechanics,scientists refer to Azerbaijan as the “world capital of mud volcanoes.”

University of Adelaide geologist Mark Tingay has studied mud volcanoes for years. “I find it amazing that an island, 400 meters wide, can appear within the space of a few hours,” he told, Popular Mechanics.

Tingay adds that these submarine features rise suddenly when internal pressure finds an exit route. In some cases, seafarers might witness pillars of flame. At Kumani Bank, no verified flames lit the sky in 2023, but the land emerged nonetheless.

Photo: Pexels

This sudden landmass appeared far from the mainland.

Formation and Erosion

Mud volcanoes form when underground pressure forces a mix of fluids, sediments, and gases up to the surface. This exodus can produce violent displays. It can also forge chunks of land that endure briefly. Kumani Bank’s ephemeral mound in 2023 lasted less than two years. Strong waves and natural forces soon whittled it away.

Experts note that the seafloor at Kumani Bank sits just a few meters under the surface. Even a moderate outflow of mud and sediment can lift the volcano’s crown above the water. That flash of creation then yields to erosion. According to NASA’s Earth Observatory, these are “weird and wonderful features that remain largely understudied and little understood.”

Sightings on the Horizon

Reports of any new island near Azerbaijan have sparked intrigue. Fishermen, sailors, or satellite analysts sometimes detect them first. Then they vanish before many have a chance to set foot on their shores. Little remains after the waters reclaim them.

Scientists continue to watch the Caspian Sea for the next appearance. They rely on new imaging technology and better data-sharing platforms to track sudden changes. The potential for fiery eruptions lingers. So does the possibility of more silent intrusions that make and unmake these ghostly stretches of ground.

Kumani Bank now fades beneath the waves. It may loom large again one day.