The conservation of submerged cultural heritage is increasingly prioritized, especially after the adoption of frameworks such as the 2001 UNESCO Convention on the Protection of the Underwater Cultural Heritage. The degradation of underwater archaeological sites, exacerbated by harsh marine conditions, requires effective in-situ restoration and environmental monitoring. Traditional approaches often rely on separate tools for mortar injection, water sampling, and sediment analysis, leading to logistical inefficiencies and operational challenges for divers. This study presents a novel battery-powered, multipurpose underwater tool designed to support and improve conservation work conducted by archaeologists and restorers. The device addresses multiple operational needs in a single solution, allowing underwater restorers to perform hydraulic mortar injection for structural consolidation, collect water samples for environmental monitoring, and extract sediment for archaeological analysis. The tool features a modular architecture, an ergonomic design for diver usability, a precision extrusion system for mortar delivery, and a rotating carousel with interchangeable cartridges. By combining these capabilities in one compact instrument, the device enhances the efficiency of underwater conservation and monitoring efforts. This integrated approach reduces the equipment burden, simplifies logistics, and enables faster, more flexible field interventions. Ultimately, the proposed system contributes to more sustainable and effective management of submerged cultural heritage, promoting more responsive and streamlined underwater conservation efforts.