A submarine having at least one first fuel cell and at least one first reformer, wherein the at least one first reformer is configured to produce hydrogen from methanol, wherein the submarine has at least one first tank (10, 11, 12, 13, 14, 15, 16, 17), a second tank (10, 11, 12, 13, 14, 15, 16, 17) and a third tank (10, 11, 12, 13, 14, 15, 16, 17), wherein the first tank (10, 11, 12, 13, 14, 15, 16, 17) being connectable to the reformer for fluid transport, wherein the second tank (10, 11, 12, 13, 14, 15, 16, 17) can be connected to the reformer for fluid transport, wherein the third tank (10, 11, 12, 13, 14, 15, 16, 17) can be connected to the reformer for fluid transport, wherein the first tank (10, 11, 12, 13, 14, 15, 16, 17) can be connected to the second tank (10, 11, 12, 13, 14, 15, 16, 17) for fluid transport, 17) for fluid transport, wherein the first tank (10, 11, 12, 13, 14, 15, 16, 17) is connectable to the third tank (10, 11, 12, 13, 14, 15, 16, 17) for fluid transport, wherein the second tank (10, 11, 12, 13, 14, 15, 16, 17) being connectable to the third tank (10, 11, 12, 13, 14, 15, 16, 17) for fluid transport, the first tank (10, 11, 12, 13, 14, 15, 16, 17) being connected on the underside to a first outlet valve (20, 21, 22, 23, 24, 25, 26, 27), the first tank (10, 11, 12, 13, 14, 15, 16, 17) being connected on the upper side to a first inlet valve (30, 31, 32, 33, 34, 35, 36, 37) at the top, that the second tank (10, 11, 12, 13, 14, 15, 16, 17) is to a second outlet valve (20, 21, 22, 23, 24, 25, 26, 27) at the bottom, that the second tank (10, 11, 12, 13, 14, 15, 16, 17) is connected at the top to a second inlet valve (30, 31, 32, 33, 34, 35, 36, 37), that the third tank (10, 11, 12, 13, 14, 15, 16, 17) is connected at the bottom to a third outlet valve (20, 21, 22, 23, 24, 25, 26, 27), and that the third tank (10, 11, 12, 13, 14, 15, 16, 17) is connected at the bottom to a third outlet valve (20, 21, 22, 23, 24, 25, 26, 27), 14, 15, 16, 17) is connected on the upper side to a third inlet valve (30, 31, 32, 33, 34, 35, 36, 37), characterised in that the first outlet valve (20, 21, 22, 23, 24, 25, 26, 27), the second outlet valve (20, 21, 22, 23, 24, 25, 26, 27) and the third outlet valve (20, 21, 22, 23, 24, 25, 26, 27) are connected to a second outlet valve (20, 21, 22, 23, 24, 25, 26, 27), 21, 22, 23, 24, 25, 26, 27) are connected via an outlet connection, wherein the first inlet valve (30, 31, 32, 33, 34, 35, 36, 37), the second inlet valve (30, 31, 32, 33, 34, 35, 36, 37) and the third inlet valve (30, 31, 32, 33, 34, 35, 36, 37) are connected via an inlet connection, 37) are connected via an inlet connection, wherein the inlet connection and the outlet connection are connected to one another via a pump (60, 101, 101, 120, 121), wherein the first tank (10, 11, 12, 13, 14, 15, 16, 17) is connected on the underside to a first methanol drain valve (80, 81, 82, 83, 84, 85, 86, 87) on the underside, that the second tank (10, 11, 12, 13, 14, 15, 16, 17) is connected to a second methanol drain valve (80, 81, 82, 83, 84, 85, 86, 87) on the underside, and that the third tank (10, 11, 12, 13, 14, 15, 16, 17) is connected to a second methanol drain valve (80, 81, 82, 83, 84, 85, 86, 87) on the underside, 17) is connected on the underside to a third methanol drain valve (80, 81, 82, 83, 84, 85, 86, 87), wherein the first methanol drain valve (80, 81, 82, 83, 84, 85, 86, 87), the second methanol drain valve (80, 81, 82, 83, 84, 85, 86, 87) and the third methanol drain valve (80, 81, 82, 83, 84, 85, 86, 87) are connected to each other via a methanol discharge valve (80, 81, 82, 83, 84, 85, 86, 87), 86, 87) are connected via a methanol discharge connection, wherein the methanol discharge connection is connected to the at least one first reformer via at least one first methanol discharge pump, wherein the first tank (10, 11, 12, 13, 14, 15, 16, 17) is connected on the underside to a first water drain valve (110, 111, 112, 113, 114, 115, 116, 117), in that the second tank (10, 11, 12, 13, 14, 15, 16, 17) is connected on the underside to a second water drain valve (110, 111, 112, 113, 114, 115, 116, 117), and in that the third tank (10, 11, 12, 13, 14, 116, 117) is connected on the underside to a second water drain valve (110, 111, 112, 113, 114, 115, 116, 117), 11, 12, 13, 14, 15, 16, 17) is connected at the underside to a third water drain valve (110, 111, 112, 113, 114, 115, 116, 117), wherein the first water drain valve (110, 111, 112, 113, 114, 115, 116, 117), the second water drain valve (110, 111, 112, 113, 114, 115, 116, 117) and the third water drain valve (110, 111, 112, 113, 114, 115, 116, 117) are connected at the underside to a third water drain valve (110, 111, 112, 113, 114, 115, 116, 117), 117) and the third water drain valve (110, 111, 112, 113, 114, 115, 116, 117) are connected via a water drain connection, wherein the water drain connection is connected to the at least one first reformer via at least one first water drain pump.