“When we’re on a mission, we dredge all day…” However, the researchers of the BOA missions (series of French oceanographic campaigns aimed at studying sunken wood and associated organisms) are far from frivolous. In fact, they are looking for something at the bottom of the sea! And as Caroline Hoyoux, PhD student in the Ultrastructural Morphology Unit of the University of Liège’s Department of Environmental Management, explains, “on the oceanographical boat, there isn’t a minute to lose.” Five, ten, fifteen times a day, the Alis’ team throws the trawl net into the sea and rakes up a blackish mass from the sea floor at a depth of 1000 or 2000 metres. The boat does not dredge randomly. Thanks to a sophisticated sonar, capable of scanning the seafloor at a depth of several thousands of metres, researchers can spot all sorts of undulations, such as underwater canyons. These rugged surfaces favour the accumulation of dead trees from the surrounding islands. A tree that dies on the beach is very likely to be snapped up by the sea. It will float for some time according to its density, but will finally sink to the seabed.