If you wish to use your Z System camera under water, you need a specialized housing for the camera, and often a specialized port for the lens. Note that some Z System models use the same housing (from some makers) while some makers use the same product naming for different housings that are customized to the camera model. The links that follow should take you to the correct page.
Z5
Z6, Z6II, Z7, Z7II
Z6III
Z8
Z9
Z50