I spoke with Scout Linden about this yesterday, he suggested I report this bug because he had no idea how to fix it. I was on the last version of the SL viewer (Mind you this issue began when I had installed it), Scout had me download the release candidate because it resolved many issues related to graphics. So I did, and the terrain below water level still appeared black. I upgraded my graphics card drivers. The land from water level and below is still black. I do not know what is causing this, but as a photographer in SL, not to mention someone who cannot even enjoy their own sim any more at ground level, this is quite disturbing. I would like to see this resolved so that I can take pictures and enjoy the view from my property. Mind