The primary aim of the project Marion Rise, which is an international program between scientists from Germany, United States and China, was to explore and sample two main working areas along the Southwest Indian Ridge in the southern Indian Ocean. The research program of expedition SO273 Marion Rise had the main objective of sampling rocks and fluids and mapping segments of the slow spreading Southwest Indian Ridge (SWIR) near Marion Island. The Northern working area was investigated during Leg 1 performed by our American partners with cruise TN365 with RV Thomas G. Thompson from 18.2. to 28.3.2019. The Southern working area was investigated by Leg 2, cruise SO273 with RV Sonne. The research program of expedition SO273 Marion Rise had the main objective of sampling rocks and fluids and mapping segments of the slow spreading Southwest Indian Ridge (SWIR) near Marion Island.