Using The Magic Tool
In addition to the Line and box tools, you can use the "Magic" tool to select tiles based on groups of the same terrain or foreground.
In the above example, I've clicked anywhere inside the top lake to select all water tiles within it. I then clicked anywhere in the bottom lake to select all water tiles within it.
The Magic tool works by taking whichever tile you've clicked and moving out from it, selecting all tiles adjacent to it (or adjacent to that) that are the same. In this way you can select whole groups of tiles, such as lakes or forests, without having to painstakingly use Box or Line tools.
Magic Tool options
By clicking "Terrain: ON" to turn it off and "Foreground: OFF" to turn it on, you can use the magic tool on foregrounds rather than terrains.
You can also turn both on and select things that have both the same foreground and the same terrain.
Selection Barrier
The selection barrier makes the Magic function stop when it hits tiles that have already been selected. This allows you to do things like select things inside a shape other than a box:
Here, I've used the "Line" tool to circle an area around the peninsula here.
With the selection tool, I click a water tile somewhere inside the shape I've drawn. Thanks to the selection barrier option, the magic tool will then select only the water tiles inside that shape.
Selecting a specific piece of landmass
Here's a technique for selecting a specific peninsula on the map:
