At the end of Pirates of the Caribbean: On Stranger Tides (2011) we can see in Syrena (mermaid) and Philip having the below conversation:
Syrena: You're hurt.
Philip: Body, only. My mind is at peace - Cause of you.
Philip: Yes. I was lost, the wind. The tides...They truly knew man's fate. For me, only you.
Syrena: Philip, I can save you. You need only ask.
Philip: I seek but one thing.
Syrena: What is that?
Philip: Forgiveness. If not for me you would never have been captured.
Philip: Forgive me.
After that Syrena kissed Philip and took him under water.
Why did she take Philip under water? Can Syrena save Philip under water?