carried on playing with terrain generation - I spend far too much time playing with my code and not enough time writing it...
The lightest shade of blue is shallow (wadeable) water while black is ocean. I generated some beach areas, but I will do a second pass to cull beach areas that are too far away from water.
Another item for the second pass: there are some islands of low area (demonic fog) inside the big areas of safe high ground. I've found a simple algorithm to identify these pesky islands so I can raise those areas up and consolidate the safe ground.
The mountain sections look a bit dull and blobby; I will try to add some high frequency noise to high areas only so they look more eroded and interesting.
Now I need to figure out a* so I can add paths between the interesting points on the map. Some paths will lead you to higher ground, others will lead you to monster nests.