[edit] You can find a less scientific / more illustrative introduction to the concept here [2].
[1] http://groups.csail.mit.edu/mac/users/wisdom/swimming.pdf
[2] http://www.brophy.net/Downloads/AIL%20Class%20on%20Reality%2...
I'm not an expert, but isn't that definitionally everywhere? Or is it that it works better when your vicinity is more curved? The paper is a bit beyond my ability to get anything from, and the summary on Wikipedia isn't much better, and also doesn't seem to match what you're implying it is.
> “Swimming in spacetime” is a geometrical motive principle that exploits the curved spacetime metric of the gravitational field to permit an extended body undergoing specific deformations in shape, to change position. In weak gravitational fields, like that of Earth, the change in position per deformation cycle would be far too small to detect, but the concept remains of interest as the only unambiguous example of reactionless motion in mainstream physics.