A historical medical treatise on the illnesses sailors face at sea, with practical observations and remedies from a 17th‑century perspective. This edition presents a rare compilation by Ludovicus Rouppe on maladies common to navigators, including early discussions of scurvy and the impact of long voyages on the body. It also contains observations about the effects of extracts and remedies used in maritime medicine, illustrating how physicians approached disease, symptoms, and treatment in its era. Readers will encounter a blend of prolegomena, practical clinical notes, and case observations that reveal how naval life shaped medical thinking. The text offers a window into historical medical reasoning, terminology, and the care given to seafaring patients during a time when long sea journeys posed unique health challenges. Overview of the shipboard environment and its influence on health during navigation. Descriptions of diseases seen in sailors, including discussions of scurvy and related symptoms. Clinical observations, symptoms, and progression of illness from the era’s perspective. Medieval-to-early‑modern remedies and the rationale behind their use. Ideal for readers of historical medicine, maritime history, and early scientific writing who want to understand how doctors documented disease and care in seafaring life.