You can make a texture {Or download an image lololol} and then make the material file for it that makes it all water-like. It wouldn't effect your default water if you did it that way. You would just texture your water/ocean in the map with the material that you made C:
I don't understand that either >:U But maybe I suggest that you find free models, and then ask for them to be converted. Your brain will explode if you try to mess with Blender lololool xD
You'd ask on the FH forums C:
They need to be convert from .max, .obj, .3ds {and many, many, more formats!} to .mesh.xml, and then you download a thing from the OGRE website to convert that .mesh.xml to a .mesh C: LONGGGGGG~ complicated. process. Lol. But here are some good websites:
http://artist-3d.com/free_3d_models/06nature_design.php (http://artist-3d.com/free_3d_models/06nature_design.php)
http://archive3d.net/ (http://archive3d.net/)
http://www.models-resource.com/ (http://www.models-resource.com/)
and
http://www.turbosquid.com/ (http://www.turbosquid.com/)
But with turbosquid, make sure the mesh is FREE before you ask someone to convert it. :3