See, I always had a method to training my recruits back in the day. I always gave them armor and weapons, good armor, crappy weapons. Then I would drop them down a hatch into a large, masterfully engraved barracks area, filled with water to the point where they COULD walk about without drowning, but still gained swimming skill. Food and booze were dropped in occasionally and beds had already been built (though can't remember if they ever actually USED them o.O;)
The only way out was a water elevator, the only way in was the trap door.
Once a recruit was sufficiently well trained that he could survive sparring with the proper military, he'd leave the boot camp by pulling a lever in the water elevator. His swimming skill by this point would be high enough that he wouldn't drown as water poured into the chamber (which had locked the door behind itself) and would lift him out of the room back to proper dwarvish land. The water was then either released into a bottomless pit or chasm is one was present on the map, or was pumped back to the surface.
Fail safes were in place, of the "set two levers only allowed to be pulled by the recruit in question" the one at the bottom would activate the elevator and lock down the other room so it wouldn't be flooded.
The one at the top emptied the elevator. The primary control room would have a third that would reopen the door once a new recruit was ready to be let out into the world.
All of this was meant to cause unnecessary deaths from "Legendary Axe Dwarf versus Recruit" sparring incidents. A by product of it was that my recruits gained legendary stats from CONSTANTLY SWIMMING ALL THE TIME
Burrows and the new system for military training have removed the need for this hideously complicated (but awesome) boot camp I used to make for my fortresses.
What did YOU make back in the days before 0.31 that you no longer have to make?