The invention concerns a system and a method for supplying breathing gas to a diver. The system is of the open circuit type and comprises a gas source consisting of a pressurized container (1), which is intended to be placed at a distance from the diver and which delivers breathing gas under a high pressure, a breathing apparatus (4) which is intended to be carried by the diver and a flexible tube (3), which connects the gas source with the breathing apparatus. The flexible tube is of the high-pressure type, the gas is conducted through the flexible tube under a pressure, which is essentially equal to the pressure delivered from the gas source, and the gas source is arranged to be able to deliver breathing gas at a pressure, which exceeds approx. 30 bars.