A retractable/deployable enclosure assembly for an open stern of a watercraft vehicle comprising a plurality of foldable sidewalls and a foldable or retractable roof which are adapted to be stowed within recesses of the pre-existing hull. The sidewalls may be stored in storage berths located under either the gunnel cap or the deck of the watercraft vehicle. The sidewalls are lifted from their respective storage berths by telescoping hydraulic lifting assemblies located in the berths wherein, as the sidewalls are lifted, sidewall sections of the sidewall are unfolded. The roof is pulled from a storage berth located under a flybridge deck into a fully horizontally erect extension of the flybridge once the sidewalls are fully deployed. The roof is adapted with a locking mechanism to prevent over-deployment once the end of the sidewall is reached. Lastly, seals may be used and are manually inserted over any remaining openings.