What kind of space craft can float on oobleck?

As you're undoubtedly aware, oobleck itself is one of the many whimsical and

brilliant creations of Dr. (Theodore) Seuss (Geisel).

In other words, as memorable as Bartholomew Cubbins' encounter with the stuff

was, oobleck is completely fictional, pretend, and made-up.

If you'd like to pick it up and run with it, then the physical and chemical properties

of oobleck are whatever you say they are ... consistent with the properties described

or demonstrated in the Dr. Seuss work of course. If Dr. Seuss never stated or

implied its density, then you get to say what it is, as you develop the story further.

Then, once you define its density, you get to tell the story of the space ship that

either floated or sank in oobleck.