Basically, as the name says, this is just a 3x3 save of basic, unmodded Dwarf Fortress where there is a volcano in the middle tile of a 3x3 embark and a river in the adjacent tiles. This is a fairly rare occurance, and I spent a few hours genning several worlds to find it for my current project. I'm uploading it so that other people who wish to play with a similar layout can do so without messing around with world gen.

I'd recommend dumping all the items I've embarked with, abandoning and reclaiming the fortress before you start playing.