There is another option: wholly designed scrapyard-junkyard maps. We allready have some ruins on the map, but imagine a wide silvery-black basalt canyon on the border of two fighting countries where long time ago great battle had place. Mass of metal is laying on its bottom, bronze and steel, cogs and wires, no natural sand or water to be seen, no one remembers what made the oryginal bottom layer.
No country was brave enought to go back and retrieve those lost resources, only nameless nomads or refugees, junk dealers or ex-pirate merchants in their desperation or hope for profit. Their homes and shops and workshops and bays all dotted on the walls of this canyon in natural or atifical caves, made from parts of fallen ships. Some of them hidden deep in safe of rock, some with proud extensions to maintain bussiness.
Oh, and don't forget about nasty changes in the weather, where ever-gloomy battlefield gets covered in fog in less than seconds, giving your enemy or you a chance to run away from deadly range of seded galeon.
