The first part of this chapter deals with the equipment used by most recreational divers. The more complex and unusual types of diving equipment that are used by technical, commercial or military diving operations are dealt with in the second part of the chapter. Attention is paid to the problems the equipment can cause, particularly for the student or novice. This is of importance in understanding the medical problems that are related to diving equipment. It may also help the reader to understand the stresses experienced by the novice diver.