Fight one: Ryan Amusements. Takes place on the end of the ride, on a scene depicting the Lighthouses that lead to Rapture. The Big Sister leaps off of the top of the lighthouse, and you notice a spear gun on her right arm. She mainly attacks with her ADAM harpoon, kicks, and her melee attacks, occasionaly shooting at you with the spear gun. When you defeat her, she drops a lockbox as she flees, containing money, ADAM, and EVE, as is customary.

 

Fight two: Pauper's Drop. After rescuing/harvesting the final little sister, you hear the usual screech a minute before she attacks. You have until then to set up. She uses the speargun more now, causing you to need to use more ranged weapons. After you beat her, you receive the spear gun, along with the same drops from your previous fight, again in the form of a lockbox, but you don't find ammo until Siren Alley. You can still upgrade it, though.

 

Fight three: Dionysus Park. Takes place right outside Stanley's security booth after you deal with all three Little Sisters. She now uses Telekinesis and Incinerate!, due to lack of spear gun. You finally get to kill her, since this is the same Big Sister you've been fighting. Drops twice the normal amount of ADAM, along with key to security booth. Also prompts comment from Lamb along lines of "You think you've beaten Big Sister, don't you?"

 

Fight four: Persephone. Outside Quarantine. You activate the airlock for the quarantine, when two Big Sisters teleport in. One has her ADAM harpoon on her left arm, the other has hers on her right. They will team up on you, one using plasmids to distract you while the other sneaks up on you, or to cover for the other as they drain some unarmed splicers for health. Once one goes down, the other will attack like the Dionysus Sister. Once she, too, goes down, you can enter the quarantine.

 

Fight five, Final Fight: Sinclair's lifeboat. This level is completely my idea, I admit. You fight one last Big Sister as the lifeboat approaches the surface. She has a pair of ADAM harpoons, but cannot use her plasmids or charge attacks. Seeing as you're underwater at this point, your options are limited to your speargun, any plasmids that aren't Electro Bolt, Summon Eleanor, Incinerate!, or Hypnotize, and your drill. After a certain point, you transition to cutscene where Delta savagely kicks the sister in the knee, snapping it. You are then given the opportunity to Rescue or Harvest the Big Sister, affecting the ending like your choices with Grace, Stanley, and Gil.