In light of the lighthouse discovery, I was inspired to go exploring furter. I swam for at least an hour along that coast, until I came to this:
It's the only thing on a little plateau island off the coast of some Horde village with similar architechture. I can't recall the name though.
There's something east and slightly north of the Thandol Span, which might be a dwarven house
I'm not sure where Thandol Span is, but further down on the coast I found this:
Check this map so see the approximate locations of these screens:
I'm so inspired to explore now that I plan are finding as many interesting locations as I can, taking screenshots, and marking their locations on this map for all to see. But I think that will wait until later levels, i.e. post-mount.