Hi, I'm trying to understand how the --generate-sea stuff works. I want to know how it decides whether an "island" is water or land. The code does not really contain sufficient comments for me to work out what it's doing. I would expect it to close coastline segments that reach the tile boundary in a direction that is consistent with the "water on the right" convention but I can't see that in the code. Can anyone help please? I hesitate to whine about contributions to mkgmap as I don't want to stop them arriving but if we can't easily work out how the code works then it doesn't bode well for maintenance and bug fixing when the original author has moved on. I have agreed to help produce a marine map of the Baltic so it would be really nice if the sea was filled in without any really major problems (flooded land, etc.) I realise that this is dependent on the performance of the MP stuff but it seems to me that generating the right polygons in the first place would be a good start. I guess that the Baltic area is probably rather a challenge for the current state of the art. Thanks, Mark