Abstract: The invention relates to a submarine comprising a device for producing electricity including a fuel cell, means for feeding oxygen gas, means for feeding hydrogen fuel, and means for discharging the gas effluents, characterized in that the fuel cell (24) is an internal reforming cell operating at a high temperature and pressure (P), the operating pressure being greater than or equal to a submerged pressure (P0) of the submarine (2), in that the oxygen gas (11) feeding means and the hydrogen fuel feeding means (15, 115) are capable of bringing the oxygen gas and the hydrogen fuel to a pressure adapted to the operating pressure, and in that the effluent (20, 220) discharge means are capable of discharging the effluents outside the submarine during diving.