A marine vessel has at least two engines installed in separate respective engine compartments that are positioned substantially horizontally adjacent to each other and are separated from each other by a wall structure defining at least one opening provided with a floodgate arrangement. The floodgate arrangement includes a gate device that is movable between a closed position, in which the gate device blocks the opening, and an open position, in which the gate device frees the opening, and a buoyancy assisted movement actuation device for moving the gate device from its closed position to its open position under the influence of rising water level.