On land, you’d struggle to find a mountain that hasn’t already been climbed. In contrast, in the deep sea there are thousands of unexplored peaks. Seamounts are submerged volcanoes, active or dormant, with foothills planted in the abyss and summits soaring up thousands of metres without breaking the sea surface.

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These hidden mountains are some of the least known, but most abundant geological features on the planet. They form a fragmented habitat that covers an area rivalling the world’s tropical rainforests. As scientists learn more about seamounts, it’s becoming clear that these dramatic montane seascapes are rich oases of life that play a crucial role across the entire global ocean.

A 2019 Nekton expedition caught these images while descending a seamount near the Astove Atoll, in the Seychelles © Nekton

Currently, there’s no definitive count of the world’s seamounts, because locating and identifying them is not easy. Estimates suggest there are between 30,000 and more than 100,000 seamounts with peaks over 1,500m high. One of the biggest is Davidson Seamount off the California coast – 42km long, 8km wide and 2,280m tall. Taller still are seamounts that rise almost 5,000m from base to peak. Add in smaller peaks, 100m and higher, and the estimated global tally reaches into the millions.

On land, you’d struggle to find a mountain that hasn’t already been climbed. In contrast, in the deep sea there are thousands of unexplored peaks. Seamounts are submerged volcanoes, active or dormant, with foothills planted in the abyss and summits soaring up thousands of metres without breaking the sea surface.

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These hidden mountains are some of the least known, but most abundant geological features on the planet. They form a fragmented habitat that covers an area rivalling the world’s tropical rainforests. As scientists learn more about seamounts, it’s becoming clear that these dramatic montane seascapes are rich oases of life that play a crucial role across the entire global ocean.

A 2019 Nekton expedition caught these images while descending a seamount near the Astove Atoll, in the Seychelles © Nekton

Currently, there’s no definitive count of the world’s seamounts, because locating and identifying them is not easy. Estimates suggest there are between 30,000 and more than 100,000 seamounts with peaks over 1,500m high. One of the biggest is Davidson Seamount off the California coast – 42km long, 8km wide and 2,280m tall. Taller still are seamounts that rise almost 5,000m from base to peak. Add in smaller peaks, 100m and higher, and the estimated global tally reaches into the millions.