There are several antonyms for the word "brake deck," which refer to the uppermost surface of a ship's deck where the braking equipment is installed. One antonym could be "acceleration deck," which would be the uppermost surface where the ship's systems for increasing speed are located. Another antonym could be "throttle deck," which would be the surface where the throttles, or controls for the ship's engine, are located. A third antonym could be "cruise deck," which would be the surface where passengers can relax and enjoy the journey, without any equipment for stopping, accelerating, or controlling the ship's speed. These antonyms demonstrate the importance and complexity of different parts of a ship's deck in ensuring safe and efficient navigation.