If you look at the first annual (Mercator), you'll find a CC3 map with the same effect (It is the same world that this picture comes from, but the map is a bit less detailed. The same style though).
The dark colour around the landmass is a glow effect, colour 248, Strength 1, Blur 600. (Values needed depend on your map of course)
Monsen got it exactly. Note though that there are two strongly blurred symbol fills around the landmass, on he OCEAN FILL and COAST FILL sheets respectively. They are not visible in this small version of the map, but you can see it better in this image.
Are you using a template from the Mercator issue of the annual? These sheets doesn't appear on regular overland maps, as they are set up to make the Mercator style. If you are using another template, you need to set them up and add effects to them yourself.
Just hit the "Sheets and Effects" button (Or from the menu: Tools -> Sheets-> Sheets and Effects). From here you can create new sheets, and define effects for them, no matter the map style.
Just remember that if you add a new sheet to a drawing, by default no draw tools will use this sheet (They use the sheets they were configured for), so you either need to actually move entities to the new sheet, or create new draw tools that utilizes the sheet. Most of the existing commands will draw on any sheet as long as you switch sheets after starting the command though.
To create a specific effects style for later use, just hit the "New" button in the sheets dialogue to save your choices, so they can be re-used in another map.
Comments
The dark colour around the landmass is a glow effect, colour 248, Strength 1, Blur 600. (Values needed depend on your map of course)
If you are using another template, you need to set them up and add effects to them yourself.
Just remember that if you add a new sheet to a drawing, by default no draw tools will use this sheet (They use the sheets they were configured for), so you either need to actually move entities to the new sheet, or create new draw tools that utilizes the sheet. Most of the existing commands will draw on any sheet as long as you switch sheets after starting the command though.
To create a specific effects style for later use, just hit the "New" button in the sheets dialogue to save your choices, so they can be re-used in another map.
Note, for 2007, you have to buy the one zip for all 12 months to get it, but the Annual has some great stuff.
Here is what I did with the old style blue map style from December, 2007.
Dwarf Home Level 1