Can this be earned in multiple playthroughs or does it have to be in one?

I never found the flooded district safe so hoping Ill find it now without having to replay the entire game :S

ANyone know?

What is 'safe cracker?' No achievement by that name, as far as I know.

I believe its a hidden achievement to crack all the safes in the game.

Hm. Doesn't show up on any list I've read.

The only safe related achievement I've heard of is "Art of the Steel."

50 achievements in this game, none have anything to do with safes apart from, 'You got the Art Dealer's safe combination for Slackjaw, but robbed the safe first'