A sick bay is a compartment in a ship used for medical purposes — the ship's hospital.
The sick bay will contain the ship's medicine chest, which may be divided into separate cabinets, such as a refrigerator for medicines requiring cold storage and a locked cabinet for controlled substances such as morphine. The sick bay and the medicine chest should be kept locked, with the keys only being available to the medical officer and the ship's master.
The term is also applied ashore by the United States Navy and Marine Corps to treatment clinics on naval stations and Marine bases.
Sick bays appear in popular science fiction franchises, such as Battlestar Galactica or the Star Trek series, as the medical facility on board a starship.