Sometimes it proves interesting to speculate about the future. What if we had more advanced technology, like that found in science fiction? If Tethys is indeed almost entirely water ice, what could it be used for?
One fascinating possibility is that of terraforming Mars. If tomorrow's "warp drive" could envelope Tethys and whisk it away from Saturn, all that water might be used to build an ocean on Sol's fourth planet. Thus, Mars might become a second blue planet. Of course, this would have to come after beefing up the Martian atmosphere.
How much ocean could Tethys offer of her body? Simple volume calculations yield a depth of nearly eight and a half kilometers on a perfectly spherical Mars. Of course, the red planet is not a perfect sphere, so there would be at least one island, if all the ice were used for this one purpose.
There are two obvious problems with this wild idea directly related to Tethys. How do you warm up all that ice to make it a liquid ocean? And how do you placate the Preserve Tethys Society, which would inevitably organize against such an effort? The first we would have to leave to that future science, along with all the other problems involved with terraforming Mars. For the second, perhaps one could offer the Society far easier visits to Tethys on nearby Mars. One could even name the ocean after that moon. Those with knowledge of Earth's past might appreciate the link to our world's own Tethys Ocean, 250 million years ago—a new bond, forever linking the three worlds.