Bryce Wayne, Batwoman of Earth-11 was created by Scott Snyder and Greg Capullo.
In this one-shot story called Batman: The Drowned, we learn more about Bryce's backstory. On Earth -11, the Atlanteans were threatening the surface world, that's how Batwoman describes it from her point of view. In actuality, the Atlanteans sued for peace.
Batwoman doesn't trust them at all and in a fight with the Atlanteans she's able to murder Aquawoman.
Furthermore, the war hasn't stopped, but in fact, the Gotham has been drowned.
In order to fight them on their terms, Bryce adapted herself, performing an auto-surgical process to become like Atlanteans.