This suggestion is simple. divide the Oceans of Middle earth into several New biomes, by this I mean making a biome out of the Bay of Belfalas, or the Gulf of Harad.
Lake Town House: floating houses found on the Long-Lake.
Ships. they would not move, but would provide intrest for those sailing the high seas. they would spawn for various factions, each with slight variation to fit that factions style.
Icebergs. spawn in some of the more Northern seas.
Proposed new Biomes:
Bay of Belfalas: already marked on the map, Gondorian, Dol-Amroth, and Pelargir ships spawn here.
Bay of Umbar: that inset bay in umbar, random ships can spawn here, but with any banners removed and replaced with new 'pirate banners', as well as unique corsair ships.
Belegaer; The Sundering Sea: sunken elven ruins spawn here, occupies the western ocean near Lindon and such areas, elven ships spawn here, heading west.
Gulf of Forochel: The area of water with an opening near the forochel waypoints, Icebergs spawn here as a new structure, though not as commonly as in the Northern Ocean
Northern Ocean: Spawns at same latitude as Forodwaith and North of that, a New Structure called iceberg spawns here, semi commonly.
Gulf of Harad: the area currently labeled on the map, structures representing ships from Harad would spawn here,
Sea of Harhudor: The area between Harhudor and Harad, harad ships spawn rarely here.
Sea of Rhun: The inland sea, Dorwinnion and Rhudel ships spawn here, maybe Dalish ones too.
Southern Sea: more tropical looking ocean around Far harad, lighter color to the water.
Eastern Ocean: Mostly empty for now, ships and such could be added along with the factions in that area
Sea of Numenor: appears upon discovery of Meneltarma, shallower than other oceans, with sunken Numenorian ruins.
River Running: raplaces the current normal river biome, spawns Dalish Ships and rarely Dwarven ones; sib-biome is the Long Lake, which spawns Dalish Ships and Floating Lake Town Houses.
Northern Anduin: the Anduin North of Emyn Muil, if possible, spawns at higher altitude than ther rivers, to allow for the falls of Rauros
Southern Anduin: spawns Gondorian and Pelargir ships, and encompasses the rest of the Anduin.
Any other rivers/oceans/lakes which need to be made their own biomes? or other Structures? or any other suggestions/critisms? comment them below, I might add a map and/or pictures of proposed structures.