Natalie Portman included swim training in preparation for her latest movie epic: 'Black Swan'

I like dance! I appreciate the athleticism and the grace. Apparently some ballerinas like swimming too. Elle Magazine conducts an interview with Mary Helen Bowers of, Ballet Beautiful, for Elle Magazine. Bowers trained Natalie Portman getting her amazingly fit and graceful for the Darren Aronofsky film: Black Swan. It opens December 3rd, 2010.

The obvious part I liked best was that Helen Bowers included swimming as part of Portman's artistic and physical development. From Elle:

Did you include any cross-training in your sessions with Portman?

I did. Ballet can be hard on your joints and when you’re on a movie set doing take after take it can become really repetitive. To give her joints a break, we’d go swimming because it allowed us to work on her endurance and elongate her muscles with zero impact. ...

[Link]

Read it to see how far she swam, how often, and what strokes.