The underwater exterior surface of a watercraft is covered by a deformable protective covering formed from compartmental sections that are dimensionally sized, shaped and mechanically connected to each other for effective attachment of the assembled covering to and removal from the hull of the watercraft. The protective covering is of a cross-sectional construction arranged to provide protection against the damaging effects of underwater explosions by minimizing related adverse physical effects on the entire hull of the watercraft as well as mechanical and electrical components associated therewith.