Abstract: Disclosed is a toilet fixture, and supporting structure therefor, especially well adapted for use on marine vehicles, such as yachts or other pleasure craft. The supporting structure provides extra lateral support for the pedestal upon which the toilet bowl is mounted; in particular, the supporting structure opposes bending moments operating on the pedestal's stem. Additionally, the supporting structure can be made into the form of a closed cover, which is effective to prevent accidental or unauthorized tampering with the plumbing entering and exiting the toilet fixture. This prevents alteration of valve settings in this plumbing. The cover can also prevent dust accumulation on this plumbing, and in the general area at which the pedestal is joined to the floor.