Diving into ellipsoid swimming pool at one focus

[A.T.]

Don't forget that the velocity of the gravity wave is depth dependent.

Yes. but if the wave period is short enough, such that the wavelength is much smaller than the average depth, this effect could be made small. At the boundary the slopes are very steep so it would not be like a shallow water wave.

It would be cool, if one could show both types of waves cause an effect at the other focus with the same impact.