The textbook was first launched in November 2009, edited by Aksel Schreiner and with the aim of providing a comprehensive, web based and freely available source of information on the health, welfare and important issues affecting those at sea. Following its success it was extensively revised and a second edition, edited by Tim Carter, was published in 2013. Given the expansion in the field of maritime medicine, along with the ongoing wide spread use of the textbook from a global audience, it was decided to begin the next revision and produce this, the third edition. Sue Stannard was appointed as chief editor in 2017 and working closely with Tim Carter, the editorial board (old and new) and many authors, some of whom had contributed to the first and second editions, the textbook has been extensively revised and produced in a different format. The most obvious revision is the new name, The Textbook of Maritime Health. This was felt to be necessary to reflect the broad nature of the specialty to include not only ‘traditional’ medical subjects but also the importance of health and wellbeing amongst seafarers. Issues such as fatigue, stress, depression and other mental health issues are seen frequently among the seafaring population. In addition, lifestyle issues and illness such as obesity, alcohol and drug use and abuse and sexually transmitted disease have become or remain a major cause of illness and injury onboard possibly contributing to medical evacuation, early repatriation and early retirement.