Problem is....
Water/land on the map seems to be restricted to areas that are pre-determined (on the map) to be land, water or both. Map_c tga is the image that defines whether the areas that support both water and land displays either water or land. ie white=land, black=water. Further problem is that the map_c.tga is somehow jumbled into cut up strips and reassembled into the image that we see when we open in an image editor. Map_c.tga_table has something to do with the layout of this image or where the mesh supports land water or both.
Map_t.tga is the image that defines which texture/material to assign to a particular part of the land area only depending on which shade of grey is painted.
Map_f.tga is for trees.
Map_h.tga is height.
Knowing this it seems that new land areas out side of the areas already predifined as land is probably impossible without knowing what specifies each area to be which.
Adding water to areas that are now land is possible only on a small level provided the area of the map supports both water and land. You can find out how much of the map this is by painting a map_c.tga of Palau white and looking at the land in FMB ingame. Of course there's the issue of working out how to unjumble map_c.tga editing it and putting it back in the same order so it shows correctly ingame. The image seems to be split up evenly horizontally 32 pixels high. If you take these strips and place them end to end they match perfectly. but then they need to be split again, aligned and possibly again before you have anything that looks like the map. This is when you would edit it. Then reverse the whole process to get an image that would define the new areas of water and display them correctly in the game. I tried this with one of the smaller maps and had little success (I was never good with jigsaw puzzles), I could imagine this being next to impossible with one of the larger maps.
I didn't try the water to see if it acted like water but I should imagine it would.
Hope this gives you a bit of info on how I think this probably works. Sorry it took a while but I had to work out how to put into words what I saw/tried..
....mmmm cigarettes and Farmers Union Iced Coffee... :lol:
Cheers, Neil