We've been playing a lot of Frostgrave so I decided to turn some of my Moedlhafen dockside bits and pieces into a Watergrave table. The frost isn't really necessary, and we've effectively been playing Sandgrave, Steppegrave, Deciduousforestgrave, and Whathaveyougrave.
So, I've started on some pieces of wreckage that simply work as rough ground, under the Frostgrave rules. The stuff should come in just as handy for 7th Voyage and pirate games, too.
Another thing that will come in handy for Frostgrave is a shed load of treasure/objective markers.