The oceans cover about 71% of the Earth’s surface, yet our understanding of the oceanic crust, mantle, and dynamic processes remains limited. A major reason is the difficulty of observing Earth's structure and seismicity beneath the oceans compared to land. To address this gap, a wide range of amphibian instruments are increasingly being used, from ocean-bottom seismometers (OBS) to distributed acoustic sensing (DAS), MERMAIDs, and other novel geophysical and environmental sensors. Together, these tools are transforming our ability to explore and monitor the oceans and the solid Earth beneath them.

Over the past two decades, these approaches have led to fascinating discoveries, from earthquake processes and subduction dynamics to mantle plumes, mid-ocean ridges, transform faults, thermal heterogeneity, and volatile cycling. They also reveal exciting new opportunities to study oceanographic, biological, and environmental processes. Yet challenges remain: large-scale deployments are costly and logistically complex, data sharing and best practices are often limited, and many valuable data sets remain inaccessible for years, reducing the long-term impact of these community investments.

This session invites contributions from the global community on the full spectrum of amphibian geophysics: from new scientific results to experiment and observable design, novel analysis methods (e.g. machine learning, data fusion, cross-disciplinary approaches) to instrument development. We particularly encourage submissions that integrate different types of amphibian instrumentation and highlight the role of ocean observations in advancing our understanding of both the oceans and the Earth’s deep interior.