On a project for Statens Vegvesen, Ruden Geo Services tested the possibility to perform seismic reflection on water. This technique is widely used in the Oil & Gas industry, but is still in a research phase on this smaller scale for geotechnical purposes. Statens Vegvesen published a nice article describing the work in the article below (in Norwegian).

Lovende refleksjonsseismiske undersøkelser i Porsgrunnselva | Statens vegvesen