A combined cooling and water braking system for a vehicle (1, 20), comprising: - a first water recirculation loop having a first heat exchanger configured to cool water flowing in the first water recirculation loop, the first water recirculation loop comprising a water conduit for transporting heat away from a propulsion device configured to generate a propulsion power for the vehicle, - a second water recirculation loop having a second heat exchanger configured to cool water flowing in the second water recirculation loop, - a retarder configured to be coupled to a pair of wheels of the vehicle, the retarder being switchable between o an inactive state in which it does not affect the rotational speed of the wheels, and o an active state in which the retarder causes the rotational speed of the wheels to be reduced, characterized in that the second water recirculation loop comprises o a first water conduit portion connecting the second heat exchanger and the retarder for enabling water braking when the retarder is in its active state, and o a closable second water conduit portion extending from the second heat exchanger for transporting heat away from said propulsion device, wherein the system is switchable between a first mode of operation and a second mode of operation, wherein o in the first mode of operation the retarder is in the inactive state and the second water conduit portion of the second water recirculation loop together with the water conduit of the first water recirculation loop transport heat away from said propulsion device, and o in the second mode of operation the retarder is in the active state and the water conduit of the first water recirculation loop transports heat away from said propulsion device, whereas the second water conduit portion of the second water recirculation loop is closed, preventing water to flow from the second heat exchanger to said propulsion device. - a first water recirculation loop having a first heat exchanger configured to cool water flowing in the first water recirculation loop, the first water recirculation loop comprising a water conduit for transporting heat away from a propulsion device configured to generate a propulsion power for the vehicle, - a second water recirculation loop having a second heat exchanger configured to cool water flowing in the second water recirculation loop, - a retarder configured to be coupled to a pair of wheels of the vehicle, the retarder being switchable between o an inactive state in which it does not affect the rotational speed of the wheels, and o an active state in which the retarder causes the rotational speed of the wheels to be reduced, o an inactive state in which it does not affect the rotational speed of the wheels, and o an active state in which the retarder causes the rotational speed of the wheels to be reduced, o a first water conduit portion connecting the second heat exchanger and the retarder for enabling water braking when the retarder is in its active state, and o a closable second water conduit portion extending from the second heat exchanger for transporting heat away from said propulsion device, o in the first mode of operation the retarder is in the inactive state and the second water conduit portion of the second water recirculation loop together with the water conduit of the first water recirculation loop transport heat away from said propulsion device, and o in the second mode of operation the retarder is in the active state and the water conduit of the first water recirculation loop transports heat away from said propulsion device, whereas the second water conduit portion of the second water recirculation loop is closed, preventing water to flow from the second heat exchanger to said propulsion device.