A team of scientists, led by Co-Chiefs Andrew McCaig and Susan Lang, boarded the JOIDES Resolution in Ponta Delgada, Portugal in the Azores Islands in the middle of the Atlantic Ocean. The ship was prepared quickly and the team was able to leave port a day early to begin the expedition, setting sail for the Atlantis Massif.

Many scientists commented that this was a very unusual way to begin an expedition with COVID protocols put in place for the crew, technical staff, and science party. Staggered meal and gym times were scheduled and masks were worn for 6 days until all crew tested negative for COVID. After the masks came off, staff morale improved immensely. For many, it felt like meeting an entirely new crew when the smiling faces finally became visible. About the time the COVID protocols were lifted, the JOIDES Resolution arrived at the first drilling location, hole AMDH-02A.

The Atlantis Massif is a unique place for geologists because the continental plates are slowly spreading apart which allows the mantle layer to push up between the crust and is relatively close to the surface compared to the rest of the sea floor. The science party on Expedition 399 is interested in reaching the mantle layer in order to study the serpentinization of olivine which could be an analog to understanding about the origins of life on Earth.