Discovered a “tropical forest” on the seabed
Paco Cardenas shows a dried sponge collected during the expedition. It is a glass sponge, so called because its skeleton is made of glass. Photo: Marcus Holmqvist
Short documentary: Several thousand metres down in the deep sea, researchers led by Paco Cárdenas discovered sponges that are likely to be entirely new to science. The biodiversity was surprising, as was the heavy swell out at sea. Now he’s back on solid ground, ready to identify the animals collected.
Last spring, Paco Cardenas took part in a three-week expedition led by Greenpeace to study life on the seabed between Norway and Greenland. With the help of a large remotely operated underwater vehicle, the expedition was able to both film and collect the animals it found on the seabed.
“We had an idea of which species might be found there but we found far more than we had expected; entire habitats were covered in sponges. I was really surprised. It’s not a desert down there but a tropical forest at a depth of 2,000 to 3,000 metres,” says Paco Cárdenas, a researcher specialising in sponges and curator at the Museum of Evolution.
After just a few dives, the team discovered several species that are probably entirely new. In the film, Paco Cardenas shows some of the most exciting discoveries made during the occasionally harrowing expedition.
Film: Marcus Holmqvist, Text: Sandra Gunnarsson
Facts: About the expedition
In May 2026, Paco Cardenas and Julio A. Díaz, both zoologists at the Museum of Evolution at Uppsala University, took part in an expedition led by Greenpeace to the Arctic to survey deep-sea wildlife. Also taking part in the expedition were four further independent researchers from Bergen, Hamburg and Madrid, as well as two researchers from Greenpeace. Greenpeace’s aim in undertaking the expedition was to map the ecosystem and help protect the area from future deep-sea mining.
The expedition set out from Ireland and then continued on to the Mohns Ridge and the Knipovich Ridge, two underwater mountain ranges in the Arctic Mid-Ocean Ridge.
The collected sponges will be preserved in the zoological collections of the Museum of Evolution, whilst the other animals will be divided between the Senckenberg Natural History Museum in Frankfurt and the University Museum of Bergen.