When returning from the open sea and you see a red buoy, you should respond by keeping the red buoy on your right (starboard) side. This is based on the navigational rule "red, right, returning," which means red buoys mark the right side of a channel when coming back to port or heading upstream. Keeping the red buoy on your right ensures you remain in the safe navigable channel and avoid hazards such as shallow waters or rocks. Red buoys are typically even-numbered and mark the starboard side of a channel when returning from sea. This rule is widely used in navigation to guide boats safely back to harbor or port.