Thanks!

It looks like it does not include the subsea elevations. Is that right?
Is a version available which includes the full extent of the heights?
I realize that its resolution in altitude would be quite a bit lower.

ImageMagick's identify utility reports that it's an 8bit grey-scale image. Is a 16 bit version possible? That would help with the vertical resolution, I think.

Sorry to be such a pest. Your help is greatly appreciated.