Scientific mission unlocks secrets of the South Sandwich Islands
A recent 35-day deep-sea expedition to the remote South Sandwich Islands has yielded a wealth of remarkable discoveries, from thriving polar ecosystems and vibrant coral gardens to suspected new species and active hydrothermal vents. Led by an international team of scientists aboard Schmidt Ocean Institute’s research vessel Falkor (too), the mission also captured the first confirmed sighting of a juvenile colossal squid –a milestone in ocean science – and uncovered signs of explosive undersea volcanism.
This ambitious voyage formed part of the Nippon Foundation–Nekton Ocean Census programme, the world’s largest initiative dedicated to accelerating the discovery of marine life. Within this framework, Ocean Census scientists spearheaded the species discovery efforts, identifying a diverse range of organisms that are likely new to science – including corals, sponges, snails, sea urchins, benthic ctenophores and sea stars. A definitive count of new species is expected later this year, following a formal taxonomic review during an Ocean Census workshop.
Alongside the biodiversity research, a complementary investigation into geohazards was conducted by the GoSouth team – a collaboration between the University of Plymouth (UK), GEOMAR Helmholtz Centre for Ocean Research Kiel (Germany) and the British Antarctic Survey (UK). Their work focused on understanding the dynamic geological forces in the region, including the risks posed by tsunamis, undersea volcanoes and earthquakes.
“This expedition has given us a glimpse into one of the most remote and biologically rich parts of our ocean. This is exactly why the Ocean Census exists – to accelerate our understanding of ocean life before it’s too late,” said Dr Michelle Taylor, head of science and expedition principal investigator at the Ocean Census, and senior lecturer at the University of Essex. “The 35 days at sea were an exciting rollercoaster of scientific discovery, the implications of which will be felt for many years to come as discoveries filter into management action.” Taylor added that Mother Nature tested the team with extreme conditions, including a subsea earthquake, tropical storm force winds with hurricane-level gusts, eight-metre (26-foot) waves and icebergs that had to be carefully navigated.
Extreme conditions, rare discoveries
Located in the South Atlantic, the South Sandwich Islands form part of a complex geologic environment characterized by hadal zone trenches, underwater volcanoes and spreading centres. These tectonic features have shaped a habitat where species evolve in isolation, resulting in life forms found nowhere else on Earth. Reaching this remote area took the Falkor (too) eight days at sea from the port of Punta Arenas, Chile.
Led by co-chief scientist Dr Jenny Gales, the GoSouth team discovered two pockmarks in the mapping data of an underwater caldera – a bowl-shaped seafloor depression created by volcanic activity. These pockmarks suggested the presence of hydrothermal activity. To investigate further, the team used a ‘nested’ approach by deploying Schmidt Ocean Institute’s remotely operated vehicle SuBastian to map the area in high resolution and confirm active venting.
This exploration revealed three hydrothermal vents in the larger pockmark and one in the smaller. Situated at a depth of 700 metres (nearly 2,300 feet), they represent some of the shallowest hydrothermal vents discovered near the South Sandwich Islands, and the only ones to date explored with a remotely operated vehicle. The tallest chimney stood four metres (13 feet) high, and all vents were teeming with life reliant on chemosynthesis, including sea snails and barnacles. Nearby, the team observed thriving coral gardens and large sponges, a combination that Taylor described as unusual.
“Discovering these hydrothermal vents was a magical moment, as they have never been seen here before,” said Gales, an associate professor in Ocean Exploration at the University of Plymouth (UK). “It’s an incredible discovery that provides valuable insights into the area’s tectonic activity. Making such a discovery is rare, and highlights the importance of ocean exploration and seafloor mapping.”
Life at the limits of the deep
In addition to the vent discoveries, the expedition yielded several other significant observations. Within the trench, scientists documented snailfish eggs laid on black coral, along with what may be a new species of sea cucumber. They also found large pumice blocks, strong indicators of explosive volcanic activity in the region. A vibrant coral garden was located west of Saunders Island at a depth of 120 metres (394 feet), adding to the area’s biodiversity profile. The team also captured the first footage of Akarotaxis aff. gouldae, a species of dragonfish identified only two years ago.
“The challenging ocean and weather conditions and the isolated location of the South Sandwich Islands capture the imagination of the boldest explorers – often the closest humans to the vessel were on the International Space Station,” said Schmidt Ocean Institute’s executive director, Dr Jyotika Virmani. “We are proud to have collaborated with Ocean Census in their mission to advance the discovery of marine life and GoSouth in their quest to better understand the geological nature of this dynamic corner of the world.”
