New Coral Gardens and Hydrothermal Vents Found in the Icy Depths of the Remote South Sandwich Islands

An Ocean Census Flagship expedition and GoSouth team of scientists found suspected new species, discovered one of the island chain’s shallowest hydrothermal vents, and explored the deepest trench in the Southern Ocean.

An international team of scientists on a recent 35-day deep sea expedition to one of the most remote island chains in the world observed thriving polar ecosystems, discovered new hydrothermal vents, coral gardens and many suspected new species. The Ocean Census Flagship expedition aboard Schmidt Ocean Institute’s research vessel Falkor (too) explored the South Sandwich Islands, including one of the coldest and most isolated submarine trenches on the planet, and also found evidence of explosive volcanism. This was the same expedition that filmed the first confirmed sighting of a juvenile colossal squid.

The expedition was part of the Nippon Foundation–Nekton Ocean Census programme, the world’s largest initiative to accelerate the discovery of ocean life. The Ocean Census scientists led the species discovery efforts, uncovering a wide range of potentially new marine life–including corals, sponges, snails, sea urchins, benthic ctenophores, and sea stars. The exact number of new species will be announced later this year following an Ocean Census workshop, where taxonomic experts will formally assess and catalogue the findings. The GoSouth team—a collaboration between the University of Plymouth (UK), GEOMAR (Germany), and the British Antarctic Survey (UK)—investigated the effects of geohazards, including tsunamis, 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.” 

Mother Nature threw everything she had at the expedition, said Taylor, including a subsea earthquake, tropical storm force winds with hurricane-level gusts, eight-metre (26-foot) waves, and icebergs to navigate.

Located in the South Atlantic, the South Sandwich Islands are part of a rich mosaic of geologic features such as hadal zone trenches, underwater volcanoes, and spreading centres — features created by tectonic forces that have supported the evolution of species found nowhere else on the planet. It took eight days for the research vessel to travel to the islands from the port of Punta Arenas, Chile. 

The GoSouth team, led by Co-Chief Scientist Dr. Jenny Gales, discovered two pockmarks in the mapping data of an underwater caldera— a bowl-shaped depression in the seafloor, left after a volcano erupts. Pockmarks can indicate hydrothermal activity. Using a “nested” approach, the team deployed Schmidt Ocean Institute’s remotely operated vehicle, SuBastian to map the pockmarks at a higher resolution and confirm the presence of vents. 

The larger pockmark contained three hydrothermal vents, and the smaller contained one. Located at 700 metres depth (nearly 2300 feet), they are one of the shallowest hydrothermal vents to have been discovered near the South Sandwich Islands, and the only ones to be explored using a remotely operated vehicle. The tallest vent chimney was four metres (13 feet), making it about as tall as a basketball hoop. Each vent was covered with an array of life dependent on chemosynthesis, including sea snails and barnacles. Thriving coral gardens and large sponges were found in close proximity to the vents–an unusual observation, said Taylor.

“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. It highlights the importance of ocean exploration and seafloor mapping.”

In addition to the vents, other notable observations during the expedition included:

• In the trench, scientists found snailfish eggs that had been laid on a black coral, as well as a potential new sea cucumber species; 

• large pumice blocks, indicating that the South Sandwich Islands are capable of explosive volcanism; 
• a vibrant coral garden located west of Saunders Island at a depth of 120 metres (394 feet); 
• Capturing the first footage of Akarotaxis aff. gouldae, a species of dragonfish that was discovered 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 discovery of marine life and GoSouth in their quest to better understand the geological nature of this dynamic corner of the world.” 

About the Organisations

The Nippon Foundation–Nekton Ocean Census is the world’s largest mission to accelerate the discovery of ocean life. Launched in April 2023 by The Nippon Foundation and Nekton, it unites philanthropy, government, science, business, media, and civil society to revolutionise how marine species are found and studied. With only 240,000 marine species documented and millions more yet to be discovered, Ocean Census is working to close critical biodiversity knowledge gaps.

Schmidt Ocean Institute was established in 2009 by Eric and Wendy Schmidt to catalyse the discoveries needed to understand our ocean, sustain life, and ensure the health of our planet through the pursuit of impactful scientific research and intelligent observation, technological advancement, open sharing of information, and public engagement, all at the highest levels of international excellence.

The University of Plymouth is renowned worldwide for its high-quality research, teaching and innovation. With a mission to Advance Knowledge and Transform Lives, the University drives the global debate in disciplines from marine and maritime science to medicine, law, computing and climate action. A three-time winner of the Queen’s Anniversary Prize for Higher and Further Education – most recently in respect of its pioneering research on microplastics pollution in the ocean – Plymouth consistently ranks among the world’s leading universities for its innovation, research and teaching in relation to the United Nations’ Sustainable Development Goals. Its growing global presence is reinforced by the 200,000 alumni it has pursuing their chosen careers right across the world.

The GEOMAR Helmholtz Centre for Ocean Research Kiel is one of the world’s leading marine research institutions. Its research covers a wide range of physical, chemical, biological and geological ocean processes, from the seabed to the atmosphere. The centre is a member of the Helmholtz Association, Germany’s largest research organisation. As part of the GoSouth team, GEOMAR was involved in researching geological processes such as underwater volcanism and hydrothermal vents during the expedition.

The British Antarctic Survey strives to uncover the secrets of the Polar Regions and the frozen regions of the Earth. Our expertise spans the depths of the oceans to the inner edge of space. Our research highlights the fragility of the Earth’s frozen environments, and what that means for our planet. We have been living and working in the extremes of Antarctica and the Arctic for over 60 years. Our scientists discovered the hole in the ozone layer and identified key evidence for climate change in ancient ice – our science continues to inform decision-makers. We provide the UK’s national polar capability by operating research stations, aircraft and Royal Research Ship Sir David Attenborough, supporting science at the poles and securing the UK’s presence in Antarctic affairs.

At the University of Essex we’re ranked 58th out of 2,152 universities assessed worldwide in the global Times Higher Education Impact Rankings 2024. University of Essex research is committed to making a difference and our scientists are at the forefront of promoting sustainable approaches from the marine sciences through to Agri-tech. The University has partnerships with leading organisations including Ocean Census, CEFAS, and the Gates Foundation – to make the world a better place. At the University of Essex, we’re big believers in the power of change to create hope for a brighter future. It’s what inspired us at the start, drives us today, and shapes our future.

Video and photos available here.