Over the last decade increasing attention has been drawn to gas hydrates in submarine environments. Interests were rising from different directions including (1) the potential of methane hydrates as future energy resource, (2) the sub-seabed storage of CO2 as solid gas hydrates, (3) the potential danger of melting gas hydrates on accelerating climate change, and (4) the role of methane hydrates in benthic ecosystems such as chemosynthetic cold-seep habitats. For all of these studies, however, a basic understanding of the behavior of gas hydrates in the natural environment is the common pre-requisite. In this session, we aim to bring together scientists from the fields of geology, physical chemistry, isotope geochemistry, biogeochemistry, numerical modeling as well as the energy and CCS sector to discuss recent knowledge on gas hydrate properties, occurrences, and reactions in marine sediments. Some of the questions we would like to address are: How and where do gas hydrates form in marine sediments? How does gas hydrate formation change the geochemistry and geomechanics of sediments and what are the gas and fluid sources? What causes gas hydrates to destabilize? What is the importance of the composition and structure of gas hydrates on its stability? Which reactions do we expect when submarine gas hydrate reservoirs destabilize? What role do benthic microorganisms play during the persistence and dissociation of submarine gas hydrates? Which are the key parameters to monitor and assess when exploiting hydrate reservoirs? We especially would like to encourage scientists who are studying gas hydrates at their stability limits – in the changing natural environment or in the area of gas hydrate production/CCS - to submit their abstracts to this session.