The Sea of Rust, is an area of unstable planetary matter and molecular flux located along Cybertron's equator, stretching from Tyrest to Polyhex to the Tagan Heights and Altihex. It constantly emits a collection of corrosive, yet relatively harmless gasses. It is Cybertron's most prominent waseland, the only other one known being the Mithril Sea.
The Hydrax Plateau rises out of the center of it. Cybertron's primary spaceport is located here, where planetary visitors must check in first.
After locating a lake of Super Energon there, Shockwave used the Sea of Rust as a location to build his replica tower of the Space Bridge Generatior. Grimlock's Lightning Strike Coalition team was drawn there to investigate strange energy readings, and they were promptly captured by Insecticons. Jazz and Cliffjumper later ended up in the Sea of Rust during their hunt for Grimlock. Fighting their way through ruins and rust storms, they eventually found the Super Energon lake and Shockwave's refinery. After destroying the refinery, the two Autobots and Lightning Strike Coalition reported back to Optimus Prime, and a huge transport was dispatched to retrieve the Super Energon from the lake.