What does the trade station look like, and what is an example of what they sell, and do they sell fish?

The Trade Station is built partially underwater and tethered 100 feet below the ocean's surface. part isn't. The building is supported by a large floating ring and has only one elevator, which is used to connect the two levels.

Items noted as sold or bartered at the station include dive skins, jet fins, and minisubs. Fish, lobsters, and periwinkles are also listed in the available items.