Embodied herein is a monohull vessel with a moonpool capable of being used offshore. The monohull vessel includes a moonpool and a deck level. A movable hatch is connected to topside of the moonpool and is countersunk beneath the deck level. A multipurpose tower is mounted on the monohull vessel. The monohull vessel includes an equipment handling system removably mounted on the vessel and a hoist system located inside the monohull vessel.