Voyager encounters a planet without a surface, a spherical construct consisting of a global-sized ocean and a gravitational containment field to maintain its planetary shape. The planet's inhabitants, the technologically advanced Moneans, cautiously visit Voyager and reveal a problem with their aquatic world - the containment field is failing and it's falling apart. With a few modifications to the Delta Flyer, Paris is able to take an away team into the ocean to examine the enormous reactor whose power prevents the sphere of water from dissipating completely. But the Moneans didn't build this reactor and they don't understand it - and their very presence in the planet's vast ocean may be the cause of the instability.
