Scope: Ground motion data on the seafloor are very special, require partly very different treatment and processing than land data. This workshop focuses on all aspects of seismic data processing related to observations on sea (and lake-) floors both with classic three-component sensors, additional pressure observations, rotation sensing and distributed acoustic sensing (DAS). Specific topics include the impact of tilting on searfloor seismometer observations, strategies for tilt correction and the use of rotation sensors for corrections; opportunities of multi-component sensing on the seafloor for example for compliance estimations; strategies for time corrections for long-term deployments (e.g. using cross-correlation methods); the observation, analysis and interpretation of exotic signals such as whales, ships, glacial processes, temperature changes, etc. and interesting science questions that can be addressed with sea(lake-)floor observations. All training will again be done using Jupyter notebooks and ObsPy and other Pythonlibraries. While primarily a training workshop participants will have the chance to present their research and get feedback from the participants and trainers. (OBS deployment in the Indian Ocean – RHUM-RUM project, Photo: H. Igel)