Large scale engineering and salvage operations are just mind blowing. I remember when they brought the USS Cole back to the US. The salvage ship, I think it was a Dutch ship, flooded its ballast tanks and submerged under the Cole, then pumped out its ballast tanks and lifted back up, with the Cole now on its deck.
It's just crazy to look at, knowing the ship riding on the back of another ship is a destroyer -- hardly a tiny vessel in its own right.