OKM GeoSeeker

The OKM GeoSeeker is not a metal detector. It is a geoelectric water and cavity locator that measures the electrical resistivity of soil layers. Four electrodes are planted in the ground in the Schlumberger array: two inject direct current while the two inner electrodes read the resulting potential difference, and from those two readings the apparent resistivity at each depth is derived. Widening the electrode spacing step by step sounds progressively deeper layers and builds a vertical section showing where resistivity changes — which is what indicates groundwater, water-bearing gravel, the water table, or voids and caves. Measurements are run wirelessly over Wi-Fi from the included Android tablet, with three scan modes: Active Scan (accurate), Active Scan (quick), and Passive Scan, which reads the ground's own natural potential without injecting any current and responds only to flowing water. The GeoSeeker is built for people who drill and plan water projects: borehole contractors, large farms, municipalities and NGOs across the Sahel and the Gulf, plus survey teams looking for caves, tunnels and underground voids. OKM states a measurement range of 5–250 m (16–820 ft). That is a best-case figure: reaching it demands a very wide electrode spread on open, suitable terrain, and resolution falls off sharply with depth, so a deep reading marks a layer boundary rather than a pinpointed target. The instrument also measures resistivity contrast, not water itself — a low-resistivity zone can be clay or brine, and a cavity is only inferred from a high-resistivity anomaly — so crossed profile lines and interpretation experience are part of the job. Everything ships in a waterproof, shock-resistant protector case with Visualizer 3D Studio Professional Edition for section analysis and volumetric 3D views, and a two-year manufacturer warranty.