This presentation introduces the HKU Depthwise HydrogeoSystem (HKU-DHS), a suite of eight innovative, low-cost technologies tailored for multi-depth monitoring across diverse hydrogeological settings, including porous media, fractured rock, and karst systems. These systems address the longstanding challenge of sparse groundwater data by enabling depth-discrete measurements that reveal critical features often overlooked by conventional methods. Manufactured using locally available components and 3D printing, these systems are designed for widespread adoption in research, education, and professional practice worldwide. In coastal hydrogeology, the system has been successfully applied in regions like the Pearl River Delta and Hong Kong in China, where it has uncovered spatial variations in CO2, CH4, DIC, radium isotopes, and other geochemical parameters, providing insights into freshwater-saline water interactions and submarine groundwater discharge. By emphasizing open-source availability and fostering global collaboration, HKU-DHS aims to transform groundwater science from a data-sparse to a data-rich field, empowering researchers and practitioners to address pressing environmental challenges such as climate adaptation, ecosystem protection, and sustainable resource management. Case studies using the HKU-DHS have demonstrated the transformative potential of high-resolution data in understanding complex groundwater systems, underscoring the importance of detailed, high-resolution sampling in driving impactful scientific discoveries.