Is the detecting head waterproof? Can I search under water?
Yes the coil is impermeable.
With regard to actual underwater detecting, this is only possible at very shallow depths, for example in a stream where the coil will only be immersed by a few centimetres. This is not due to any waterproofing problem, but rather because the wireless radio link cannot pass through a greater volume of water.
We will in the future be offering a special accessory, a passive waveguide (not powered) which will clip onto the coil and allow it to operate when immersed more: deeply: https://www.xpmetaldetectors.com/es/produits/accesorios/accesorios-de-sellado.php