On her official blog, Grey's Anatomy creator and executive producer Shonda Rhimes - who wrote "Walk On Water" as well as the second and third parts of this three-episode extravaganza - talks a little bit about it.
Shonda's full thoughts on the episode can be viewed by following the link above. Here's an excerpt about "Walk On Water" and specifrically Meredith, in which Rhimes explains some of the symbolism involved, and swears she didn't just throw our girl off a pier for no reason.
Ferry boats are awesome and, in fact, very safe. Ferry boats are amazing.
Ferry boats are a metaphor for Meredith, you know.
What I was interested in was Meredith and how she was doing after being hurt by her mother. And the devastation of the ferry boat was the best way to physicalize Meredith's pain.
The little girl? She's also a metaphor for Mer. A motherless lost girl who can't speak for herself and disappears? Okay, that's too obvious. But you all know Meredith's been doing a dance with death for some time. Y'all know that if you've been watching. She's dark, our girl. She's dark and twisty. And I worry about her.
Now, I'm really worried about her because she's in the water and I want to be clear with you: I don't put people in the water for no reason. Meredith's got issues, she's got serious Mommy issues and she's broken and she's in the water.
I killed Denny (Jeffrey Dean Morgan).
I blew up Dylan (Kyle Chandler).
I'm not entirely playing by the rules of TV here.
There's a point. And it's coming. [I have my] fingers and toes crossed that it works.
Because what happens next... well, just wait and see.