Alright - now we're getting somewhere!
We knew how warped and soft the floors were, but didn't know exactly why. Surely, it must just be all rotten under there, so let's find out.
Welcome to Surprise #1: The subfloors were made of particle board. Yes, you read correctly.
If you're not aware of the differences between particle board and real plywood, this junk you see above expands and warps with humidity. We live on a lake. Why on earth would you put that on your floors?!? The good news is that we know what the problem was. Now we needed to decide: do we simply add a layer of plywood on top of this stuff, or rip it all out and replace them? Obviously replacing them is the best solution.
That is, until we peeled away the old linoleum floors. Little did we know, they used 3" nails to fasten the floors, not screws. As if having to chisel away and remove every single nail was grueling enough, we then enter the 2 small rooms.
Again, peeled away the vinyl floors, and what do we find? The glued piece of the vinyl stays stuck. Everywhere. Which means all the nails are hidden. Which means we now have to actually chisel away that layer of white (see above) in order to even get to the nails! Argh! Luckily, my father-in-law stopped in just in time... he volunteered to do this part! :)
Whew. Well now that's done. Surely it'll be smooth sailing now!