One of the key steps in nanotechnology is our ability to engineer and fabricate low-dimensional nano-objects, such as quantum dots, nanowires, two-dimensional atomic layers or three-dimensional nano-porous systems. Here we report evidence of nanotunnel opening within the subsurface region of a wide band-gap semiconductor, silicon carbide. Such an effect is induced by selective hydrogen/deuterium interaction at the surface, which possesses intrinsic compressive stress. This finding is established with a combination of ab-initio computations, vibrational spectroscopy and synchrotron-radiation-based photoemission. Hydrogen/deuterium-induced puckering of the subsurface Si atoms marks the critical step in this nanotunnel opening. Depending on hydrogen/deuterium coverages, the nanotunnels are either metallic or semiconducting. Dangling bonds generated inside the nanotunnel offer a promising template to capture atoms or molecules. These features open nano-tailoring capabilities towards advanced applications in electronics, chemistry, storage, sensors or biotechnology. Understanding and controlling such a mechanism open routes towards surface/interface functionalization.