"Walk On Water" is the fifteenth episode of the third season of Grey's Anatomy and the 51st produced episode of the series. It is also the 51st produced episode of the Grey's Anatomy franchise. It was broadcast on February 8, 2007.
A major disaster challenges the interns like never before as they deal with the aftermath of a cargo ship colliding with a ferryboat. Derek worries that Meredith is letting her mother's critisim affect her while Cristina and Burke discuss how best to tell others about their engagement. Meanwhile, Izzie's surgical skills are put to the ultimate test by an emergent situation and Alex makes a discovery at the crash site.
- "Dissapearances happen in science. Disease can suddenly fade away; tumours go missing; we open someone up to discover the cancer is gone. It's unexplained, it's rare, but it happens. We call it misdiagnosis, say we never saw it in the first place. Any explanation but the truth, that life is full of vanishing acts. If something that we didn't know we had disappears, do we miss it?"
- "The Hop" - Radio Citizen
- "Opposite Direction" - Union of Knives
- "Liar" - 8MM
- "Make This Go On Forever" - Snow Patrol
This episodes' title references the song Walk On Water, originally sung by Aerosmith
- This episode features no closing voiceover.