Surface supplied diving refers to divers using equipment supplied with breathing gas using an umbilical cord from the surface, often from a diving support vessel but possibly, indirectly via a diving bell. SCUBA, which is commonly used in recreational diving, is the main alternative to surface supplied diving equipment.

Surface supplied diving equipment and techniques are mainly used in professional diving or military diving due to the increased cost and complexity of buying and operating the equipment. This type of equipment is used in saturation diving. Divers almost always wear diving helmets or full face diving masks when being supplied from the surface. Also, there is the spherical copper helmet with brass and glass windows of the historical standard diving dress.

Surface supplied diving is becoming less common because Remotely Operated Diving Vehicles now accomplish many of the tasks previously only carried out by divers. Surface supplied diving is also generally considered more dangerous than Scuba diving, since damage or tearing of the umbilical oxygen cord while a diver is submerged almost always results in death by drowning.