A 1987 study conducted by the Japanese research team from Waseda University (Tokyo) examined the southern and northern parts and areas in front of the Sphinx's forepaws with the help of ultrasound in an effort to find hidden spaces beneath the surface.

They came to the conclusion that there is a depth of 3 meters south of the Sphinx. They have found evidence that there is a system of corridors or water canals that goes further beyond the place where the Sphinx is located. In the northern part of the Sphinx, there is a canal that corresponds to its dimensions on the southern side. It led the scientist to believe that this is the same corridor that leads north-south direction directly under the Sphinx.

In front of the Sphinx, at the level of the front paws, the scientists identified additional voids one to two meters deep. They also concluded that this space was clearly connected to other spaces they found in other parts of the subsoil on which the Sphinx stands, and that there are far more cavities than we know so far.

They also found evidence of the existence of a corridor that leads directly to the Great Pyramid and is connected to the lowest chamber - the so-called unfinished chamber of the Great Pyramid.