The Geovizer is the Rolls Royce of Metal Detection. It is designed by Russians, through the Novosibirsk Academy of Sciences, to find treasures buried up to 13 feet (4 meters). This electromagnetic induction scanner uses several frequencies at once, unlike today’s georadars. Just scan the floor with it passing over it.
It allows to find objects from 4 inches (10 cm) in diameter. It is specialized in the accumulation of coins and metal bars. It can also be useful on construction sites to locate foundations, pipelines. It generates 3D results that must then be interpreted.
The Geovizer will soon be available, it is already indicated at a price of 10,000 dollars on some online shops dedicated to detection.
Attention, find out about the law beforehand. You must have the agreement of the local prefecture to have the right to use such devices. But also, the one of the owner of the land in question. Or from the town hall, if the land is public.