You get drowned by 3 Elizabeths. Booker is escorting Elizabeth the entire game. His initials are B.D. Elizabeth's dress is nearly identical to the Little Sisters. One of the audio logs say tech came through the tears (vigors = plasmids, and Songbird connected to Big Daddy) The game strongly suggests Bioshock Infinite and 1 are different permutations of the same story. (IE: the songs they restyled to 1912 musical era) "Constants and variables" thing the game repeats over and over where the man, city and downfall thing are constants.
Maybe it's just me having this problem but the way this game does directional sound is just awful. I can only hear things that are directly in front of or behind me. It's pretty annoying.
Actually, now that I've thought about it, being able to use the bathysphere is what suggests that more anything. If you remember, only those with Ryan's genetics could use them.