Deep-seeking 3D ground scanners open up targets that a standard coil machine will never reach: caches buried meters down, voids like tunnels and chambers, and large relics hidden under heavily mineralized ground. Groundtech, a Conrad brand, builds exactly this kind of equipment, and Serious Detecting is an authorized US dealer for the full range. This guide explains how the technology works, what depth claims really mean, how Groundtech compares to alternatives like ground penetrating radar, and walks through every model we carry – complete with specs, pricing, and package contents – so you can match the right tool to your hunting goals and budget.
You can browse the full range any time on our Groundtech collection page. Below, we go deeper on what each model does well and who it is for.
How Groundtech 3D ground scanners work
Most hobby detectors use a search coil that induces an electromagnetic field a foot or two into the soil and listens for the response of nearby metal. Groundtech ground scanners work on a fundamentally different principle. They are gradiometers: instead of transmitting a signal, they use dual sensors (Groundtech's CN-D and MFS sensor systems) to passively measure tiny variations in the earth's natural magnetic field, with sensitivities of ±2000 µT on the GR series and ±3000 µT on the A2 series. Those variations reveal buried metal masses – and, just as importantly, non-metal anomalies like cavities, tunnels, chambers, and soil disturbances that often mark a grave, cellar, or old dig site.
The scan data is rendered as color-coded 3D graphics, either on a built-in HD screen or in the Groundtech mobile app over Bluetooth. Different colors separate magnetic (ferrous) metals such as iron and steel from non-magnetic (non-ferrous) finds such as gold, silver, and copper, and they highlight empty spaces and buried structures. Every unit runs a fast 240 MHz processor with a 12-bit A/D converter, so results appear in real time as you walk your survey grid.
The hybrid models: 3D scanner plus pulse induction detector
Several models in the lineup are hybrids that pair the 3D underground scanner with a built-in 1 kHz pulse induction (PI) metal detector. Pulse induction is the technology of choice for saltwater beaches and heavily mineralized ground, where standard VLF machines chatter and lose depth. A hybrid therefore gives you two workflows in one device: map deep anomalies with the scanner, then sweep and discriminate targets in the upper soil layers (down to roughly 3 meters, depending on target size) with the PI detector. If you have been searching for a deep seeking metal detector that also works as a practical everyday machine, this is that middle ground.
3D ground scanner vs. ground penetrating radar (GPR)
People often ask whether they should buy a ground penetrating radar for treasure hunting instead. GPR actively transmits radio pulses into the soil and reads reflections, which makes it powerful but also expensive (professional GPR carts typically start north of $15,000), heavy, and demanding to interpret – and its performance drops sharply in wet clay and conductive soils. A gradiometer-based 3D ground scanner is passive, far lighter (the GR-3 weighs 1.3 lbs), a fraction of the price, and specifically tuned to the two things treasure hunters care about most: metal masses and voids. For archaeological survey, cache hunting, and cavity detection on a realistic budget, a 3D scanner is usually the more practical instrument.
A note on "long range" locators
If you have been researching long range metal detectors – handheld dowsing-style rods that claim to sense gold from hundreds of meters away – be aware that no such device has ever passed a controlled test, and they contain no measurable sensing technology. Groundtech scanners are the opposite: they measure a real physical quantity (magnetic field gradients), record it, and render it as data you can inspect, repeat, and verify. If a deep target is worth digging, it is worth confirming with real measurements first.
What "up to 20 meters" really means: honest depth expectations
Every deep-seeking manufacturer quotes maximum depths, and they all depend on the same variables. The quoted figures (7 m for the GR-3, 15 m for the GR-3 PLUS and GR-4 family, 20 m for the A2 series) assume a large target in cooperative soil. In practice:
- Target size drives depth. A buried cauldron, chest, or tunnel can be resolved many meters down. A single coin cannot be seen at 15 meters by any technology on the market – anyone who tells you otherwise is selling fiction.
- Soil matters. Homogeneous, undisturbed soil produces clean data. Ground full of modern iron trash, rebar, or fill dirt produces noisy scans that take practice to interpret.
- Voids show up well. Because cavities create a distinct signature against surrounding soil, tunnels, chambers, and graves are among the most reliable deep targets for a gradiometer.
- Technique matters. Walking a consistent grid at a steady pace, keeping the sensor at a constant height, and removing metal from your person (boots, phone, belt) all dramatically improve scan quality. Re-scan any promising anomaly from a perpendicular direction before you dig.
Buy on this basis and you will be satisfied: these are instruments for large, deep targets and structures, and the hybrid models add conventional detecting for everything shallower.
The Groundtech lineup at a glance
Serious Detecting carries six Groundtech models, ranging from a lightweight wireless scanner to a professional 3-in-1 geophysical system. Here is how they compare.
| Model | Type | Max scan depth | Display | Best for |
|---|---|---|---|---|
| GR-3 | Wireless 3D scanner | Up to 7 m (23 ft) | Phone/tablet app | First deep-seeker, maximum portability |
| GR-3 PLUS | Wireless 3D scanner | Up to 15 m (49 ft) | Phone/tablet app | Same light wand, double the depth |
| GR-4 | 3D scanner with screen | Up to 15 m (49 ft) | Built-in color display | Standalone scanning, no phone needed |
| GR-4 DUAL | Hybrid scanner + PI detector | 15 m scan / 3 m detect | Built-in HD screen | Deep mapping plus a real metal detector |
| A2 | Hybrid scanner + PI detector | Up to 20 m (65 ft) | Built-in HD screen | Maximum depth, two coils included |
| A2 GEO | 3-in-1 scanner, PI detector, geo-electric | Up to 20 m (65 ft) | Built-in HD screen | Professional surveys, groundwater and cavities |
| IQ Pointer | PI pinpointer | Recovery tool | LED signal bar | Target recovery in mineralized ground and saltwater |
| IQ Detect | PI detector with fixed 7" coil | Recovery tool | LED signal bar | Scuba and surf recovery, black sand beaches |
Groundtech GR-3: the lightweight entry point
The Groundtech GR-3 is the easiest way into deep-seeking. It is an ultra-compact, completely wireless wand that weighs only 600 grams (1.3 lbs), with no battery packs or cables to manage. It reaches scanning depths of up to 7 meters (about 23 feet) and sends color-coded 3D results to the Groundtech app over Bluetooth.
It offers four scanning modes (Automatic Ground Scan, Manual Ground Scan, Live Scan, and a Pinpointer function), runs about 8 hours per charge, and charges over USB-C. If you want to learn what a 3D scanner can do without a large investment, this is where to start.
Groundtech GR-3 PLUS: same wand, double the depth
The Groundtech GR-3 PLUS keeps the same 600-gram cordless design but upgrades the internal sensor system to reach up to 15 meters (about 49 feet), double the base model. It shares the four scanning modes and the real-time 3D app visualization, separating magnetic metals from non-magnetic treasure.
If portability matters to you but 7 meters feels limiting, the GR-3 PLUS is the natural step.
Groundtech GR-4: standalone 3D scanning
The Groundtech GR-4 is the next-generation flagship scanner. Its big advantage is the built-in high-resolution color display, so you can scan, switch modes, and read results in the field without a phone or tablet. It uses MFS-2 dual sensor technology, reaches up to 15 meters, and still syncs to the G-Portal app for full 3D and 4D analysis.
A foldable modular body, adjustable grip, and removable sensor module make it comfortable for long days. Choose the GR-4 over the GR-3 PLUS if you prefer an all-in-one unit with a screen rather than a wand that depends on your phone.
Groundtech GR-4 DUAL: a scanner and a metal detector in one
The Groundtech GR-4 DUAL adds a 1 kHz pulse induction metal detector to the GR-4 platform. You get 3D ground scanning down to 15 meters plus conventional PI detecting to about 3 meters (10 feet), with a PiD35 search coil included. Six scanning modes cover everything from quick detector sweeps to advanced discrimination that separates ferrous junk from gold, silver, and copper.
This is the best value if you want one device that both maps deep anomalies and works as a serious detector on the upper soil layers.
Groundtech A2: maximum depth with a standalone screen
The Groundtech A2 is a hybrid that pushes 3D scanning depth to 20 meters (about 65 feet) using upgraded MFS-3 dual sensors, while including a 1 kHz pulse induction detector. It runs standalone thanks to its built-in HD color screen and ships with two detector coils (PiD25 and PiD30) plus a premium headset. Six scanning modes and G-Portal app analysis round it out.
Step up to the A2 when you need more depth than the GR-4 family and want professional-grade hardware in a self-contained unit.
Groundtech A2 GEO: the 3-in-1 professional system
The Groundtech A2 GEO is the top of the range. It combines three instruments in one: a 20-meter 3D ground scanner, a 1 kHz pulse induction detector, and an integrated geo-electric resistivity system for mapping groundwater, deep cavities, and burial chambers across multiple survey lines. It offers eight scanning modes, a built-in HD screen, and analysis through both the G-Portal app and the Groundtech Suite.
The A2 GEO is built for advanced archaeologists, utility locators, and serious treasure hunters who need the deepest, most complete picture of what is underground. It ships with the MFS-3 sensor module, two detector coils, four conductive probes, four 25 m conductor cables, and a heavy-duty field bag.
Which Groundtech is right for you?
Here is a quick way to narrow it down:
- You want the lightest, simplest deep-seeker and you already carry a phone: choose the GR-3 (or the GR-3 PLUS for double the depth).
- You want an all-in-one scanner with a screen and no phone dependence: choose the GR-4.
- You want deep scanning and a true metal detector in one device: choose the GR-4 DUAL.
- You need maximum 20-meter depth in a standalone hybrid: choose the A2.
- You run professional surveys and need geo-electric resistivity for water and cavities: choose the A2 GEO.
Real-world use cases
Cache and hoard hunting. Buried strongboxes, jars of coins, and wartime caches are classic gradiometer targets: compact metal masses at depths a coil machine cannot reach. Scan a grid, confirm the anomaly from two directions, then recover with the PI detector and a pinpointer as you dig down.
Relic and battlefield research. Large iron and non-ferrous objects – cannon fragments, wagon hardware, weapon caches – produce strong magnetic signatures. The color separation between ferrous and non-ferrous responses helps you prioritize which anomalies justify a deep excavation.
Archaeology and cavity detection. Because voids read clearly against surrounding soil, these systems double as a cavity detector for tunnels, crypts, cisterns, and chambers – a non-invasive way to survey a site before anyone puts a shovel in the ground. The A2 GEO's resistivity system extends this to groundwater and very deep structures.
Gold prospecting and beach hunting. For individual gold nuggets and jewelry, the hybrids' pulse induction side is the right tool – PI is renowned as a metal detector technology for gold country and saltwater beaches precisely because it ignores mineralization. Use the scanner side for larger, deeper possibilities like flood-layer accumulations or buried equipment.
Which Groundtech is right for you?
Here is a quick way to narrow it down:
- You want the lightest, simplest deep-seeker and you already carry a phone: choose the GR-3 – or the GR-3 PLUS for double the depth at $300 more.
- You want an all-in-one scanner with a screen and no phone dependence: choose the GR-4.
- You want deep scanning and a true pulse induction metal detector in one device: choose the GR-4 DUAL – the best value in the range.
- You need maximum 20-meter depth in a standalone hybrid: choose the A2, which also adds a second coil and headset.
- You run professional surveys and need geo-electric resistivity for water and cavities: choose the A2 GEO.
Whichever system you pick, add the IQ Pointer to your kit – once you have dug a meter or more down to an anomaly, a PI pinpointer saves an enormous amount of time locating the target in the spoil.
Why buy your Groundtech from Serious Detecting
Every Groundtech unit we sell is sourced as an authorized US dealer, so it arrives with the full 2-year manufacturer warranty and genuine accessories. Deep-seeking equipment is a considered purchase: if you are not sure which model fits your sites and budget, reach out and we will talk it through before you buy.
Frequently asked questions
- What is a 3D ground scanner?
- A 3D ground scanner uses dual gradiometer sensors to measure variations in the earth's electromagnetic field and renders them as color-coded 3D graphics. It reveals deeply buried metals, cavities, and structures that a standard coil detector cannot reach.
- How deep can Groundtech detectors go?
- It depends on the model, soil, and target size. The GR-3 reaches up to 7 meters, the GR-3 PLUS and GR-4 family up to 15 meters, and the A2 and A2 GEO up to 20 meters with the 3D scanning system.
- What is the difference between the GR-4 and the GR-4 DUAL?
- The GR-4 is a 3D ground scanner only. The GR-4 DUAL adds an integrated 1 kHz pulse induction metal detector with a search coil, so it works both as a deep scanner (up to 15 m) and a conventional detector (up to about 3 m).
- Do I need a smartphone to use a Groundtech scanner?
- The GR-3 and GR-3 PLUS display results in the Groundtech app on a phone or tablet. The GR-4, GR-4 DUAL, A2, and A2 GEO have a built-in HD screen and run standalone, while still offering app analysis.
- Which Groundtech is best for saltwater beaches and mineralized ground?
- The hybrid models (GR-4 DUAL, A2, and A2 GEO) include a pulse induction detector, which is well suited to saltwater and heavily mineralized soil in addition to deep 3D scanning.
- Are Groundtech detectors covered by warranty?
- Yes. Every model includes a 2-year manufacturer warranty, and Serious Detecting is an authorized US dealer.
