I have just recovered from one of these moments.
I have an embark site which I fell in love with the moment I saw where the Dwarves landed. It is in the world of The Future Realms, on the shore of the Shriveled Ocean of Sucking. The 6x6 is about 2/3 ocean, and frozen. There is a magma pipe open to the surface. There are no trees or other vegetation. There is an aquifer. I was uncertain how I felt about it until I embarked, and my Dwarves landed on the very edge of the beach, just on the dry side of the waterline. Of course, as soon as I un-paused the game, the surf washed over them. It was as if they had been shipwrecked, and floated ashore with nothing but this one miserable wagon loaded with booze, plump helmets and their spawn, turtles, one rope, two picks, one axe, two cats, two dogs, and two draft beasts of dis-similar species.
The first two levels of this site are sand and loam with very, very few basalt inclusions over near the ocean. I mined those for the three vital workshops and a few critical pieces of furniture. There was nothing left over for making mechanisms for trade, so when the Autumn caravan arrived, I had to trade home-grown plump helmets for a few sticks of tower-cap and a couple of spare barrels. The plump helmets were being stored without barrels so that I could reserve the barrels for booze.
The next two levels of this site are aquifer. We tunnelled through dirt to the obsidian border of the magma pipe, and dug down three levels. I noticed that they encountered damp stone, so I had them dig one more level. Now stone was available in ample supply and the future looked bright, if a bit heavy on plump helmets and Dwarven wine. We actually got migrants in mid-winter - 19 of them all at once!
Stone was being dragged to the workshops in great piles. We had found bauxite, and that was already safely stored and forbidden. We had obsidian, basalt, mudstone, and a few other miscellaneous types, as well as a number of gems.
It was a little crowded on the stair landing on the first rock level under the aquifer with all those Dwarves hauling stone from the layer below, and I thought to myself that it was just damp stone, right? Like under a pond? So I told them to dig out another 5 squares ...
ARGH....
I abandoned the fortress, deleted the region, and started the world over again so I could have that site without my mess.