Pounder
Phaethon was here
The two files that are used for Landmark Sea are LwCSO and LwSSS, just make modifications to a wCSO file and a wSSS file, and then rename them LwCSO and LwSSS.
The wCSO file has all the transition tiles between coast sea and ocean. All of the tiles with any piece of sea in the transition tile can be used for the landmark sea in the editor.
I have found that it is best to use the wCSO for terrain type mods.
Here is an example of a wCSO mod (http://forums.civfanatics.com/showpost.php?p=11623914&postcount=121):
Use the wSSS for random things like birds, fish and such.
Here is an example of a wSSS mod (http://forums.civfanatics.com/showthread.php?t=442450):
As far as full Landmark Sea tiles go: If you have problems displaying every landmark tile properly, it's because the the LwCSO file has one full landmark sea tile in it's graphics. So if you want to mod the landmark sea file (LwSSS), then you will also have to mod that one LwCSO tile.
Landmark sea is the only landmark water that is available in the editor, but it will always skip/miss some of the selected tiles if you don't mod the LwCSO. That tile is the center tile on the wCSO.
The wCSO file has all the transition tiles between coast sea and ocean. All of the tiles with any piece of sea in the transition tile can be used for the landmark sea in the editor.
I have found that it is best to use the wCSO for terrain type mods.
Here is an example of a wCSO mod (http://forums.civfanatics.com/showpost.php?p=11623914&postcount=121):

Use the wSSS for random things like birds, fish and such.
Here is an example of a wSSS mod (http://forums.civfanatics.com/showthread.php?t=442450):

As far as full Landmark Sea tiles go: If you have problems displaying every landmark tile properly, it's because the the LwCSO file has one full landmark sea tile in it's graphics. So if you want to mod the landmark sea file (LwSSS), then you will also have to mod that one LwCSO tile.
Landmark sea is the only landmark water that is available in the editor, but it will always skip/miss some of the selected tiles if you don't mod the LwCSO. That tile is the center tile on the wCSO.