During the week of 05 to 09 October, the first action of the MSCA ITN H2020 GMOS-TRAIN project (www.gmos-train.eu) was launched under the responsibility of Lars Eric Heimburger-Boavida, with practical training for doctoral students from the maritime work programme. All participants were trained in clean sampling techniques, mercury species measurements and incubation experiments. Doctoral students from AMU-MIO, the University of Pau, Géosciences Environnement Toulouse, IFREMER, Stockholm University and the Jozef Stephan Institute will soon be working in the Atlantic, Arctic, Indian and Southern Oceans, as well as in the Mediterranean and Baltic Seas, using the same analytical techniques. Special thanks to David Amouroux and Emmanuel Tessier (IPREM), SSL@MM and Antedon 2.