The city itself is a huge wasteland, with just parts of buildings sticking out of the sand. It consists of one large map leading the new coast created by the rising of the Gulf of Mexico, where the Corpus Christi Naval Base has been submerged. Oddly enough, there is also a strange plant thing sticking up out of the water.
Getting into the base itself requires traversing two medium underwater maps where mutated fish and hostile plants will be encountered. The base is made up of five medium to large maps containing robot sentries and increasing amounts of plantlife towards the boss area. It swiftly becomes a jungle like environment very similar to Vault 39.
The player character has to visit the docks, where Jackal raiders wait for him. These are the cream of the crop, though. Full power armor and everything. After taking them out, the player character finds an underwater suit and it's time to visit the base and see who's behind it all.
After the player character has fought their way into and through the naval base, they will move on to the final fight with Reese himself. The Cipher has vine things, and manages to merge himself with the plant walls. It is his hatred of the Brotherhood that has led him here. And his hatred of the player character. Then, in classic Fallout fashion, the player character must overload the modified G.E.C.K. and get the hell out of dodge before it all gets blown to hell.