A boat.

S/V Ocean Surveyor is a 38-meter long and 12-meter wide fiberglass catamaran designed for oceanic voyages.

Photo: Carl-Erik Alnavik/SGU

Marine Geological Mapping

Unlike terrestrial mapping, direct contact with the seafloor is usually not possible during marine geological surveys. Therefore, advanced instruments mounted on SGU's research vessel Ocean Surveyor and research boat Ugglan are essential in this operation.

In shallower waters, satellite data, aerial photographs, and elevation data from lidar systems can be used. However, further offshore and in the coastal zone, the surveys are practically conducted exclusively from ships and boats. To image the seafloor from vessels, a variety of acoustic methods are primarily employed, depending on the specific objectives. Sound propagates easily and over long distances in water, unlike light and radio waves, which quickly attenuate and fade. Therefore, hydroacoustic measurement systems are currently the optimal choice for marine geological mapping.

The acoustic survey systems can either image the surface of the seafloor or have the ability to penetrate loose sediments as well as underlying bedrock, providing a vertical view of the seafloor's composition.

Sampling systems are also used during the surveys to collect sediment samples and sediment cores. Underwater cameras are employed to photograph or film the seafloor. These bottom samples and photographs are necessary to accurately interpret the acoustic imaging signatures and determine the detailed characteristics of the sediments. Sediment samples from the seafloor are also analyzed to map environmental pollutants.

SGU has two vessels in its fleet for marine geological mapping. The S/V Ocean Surveyor is used for water depths over 6–10 meters, while the research boat S/V Ugglan is utilized in shallower areas (from 2–3 meters deep).

Last reviewed 2023-06-12