Is There a Chamber Beneath the Sphinx?

The idea that there is a chamber beneath the Great Sphinx at Giza likely has its roots in antiquity. In his Natural History, Pliny wrote:

In front of them [i.e. The Giza Pyramids] is the Sphinx, which deserves to be described even more than they, and yet the Egyptians have passed it over in silence. The inhabitants of the region regard it as a deity. They are of the opinion that a King Harmais is buried inside it... [Book 36 XVII]

But it was Edgar Cayce, the "sleeping prophet," who popularized the idea of a secret chamber associated with the Sphinx. According to Cayce, there is a "Hall of Records" with an entrance to be found between the paws of the Sphinx. In answer to the request, "Give in detail what the sealed room contains," Cayce answered:

A record of Atlantis from the beginning of those periods when the Spirit took form, or began the encasements in that land; and the developments of the peoples throughout their sojourn; together with the record of the first destruction, and the changes that took place in the land; with the record of the sojournings of the peoples and their varied activities in other lands, and a record of the meetings of all the nations or lands, for the activities in the destruction of Atlantis; and the building of the pyramid of initiation, together with whom, what, and where the opening of the records would come, that are as copies from the sunken Atlantis. For with the change, it [Atlantis] must rise again. In position, this lies -- as the sun rises from the waters -- as the line of the shadows (or light) falls between the paws of the Sphinx; that was set later as the sentinel or guard and which may not be entered from the connecting chambers from the Sphinx's right paw until the time has been fulfilled when the changes must be active in this sphere of man's experience. Then [it lies] between the Sphinx and the river. [378-16; Oct 29, 1933]

In the years to come, Cayce would speak more on the subject of the so-called Hall of Records:

It would be well if this entity were to seek either of the three phases of the ways and means in which those records of the activities of individuals were preserved -- the one in the Atlantean land, that sank, which will rise and is rising again; another in the place of the records that leadeth from the Sphinx to the hall of records, in the Egyptian land; and another in the Aryan or Yucatan land, where the temple there is overshadowing same. [2012-1; Sep 25, 1939]
... the entity joined with those who were active in putting the records in forms that were partially of the old characters of the ancient or early Egyptian, and part in the newer form of the Atlanteans. These may be found, especially when the house or tomb of records is opened, in a few years from now. [2537-1; Jul 17, 1941]
... [the entity] was among the first to set the records that are yet to be discovered or yet to be had of those activities in the Atlantean land, and for the preservation of data that is yet to be found from the chambers of the way between the Sphinx and the pyramid of records. [3575-2; Jan 20, 1944. Excerpts from Cayce, Edgar. On Atlantis. New York: Warner Books, 1968.]

The Rosicrucians seized the idea of a secret chamber as a place of initiation. (For more information and diagrams of their "Subterranean Hall," see The Rosicrucian View.) In more recent years, the theory of yet undiscovered chambers in the area of the Sphinx has been popularized by authors quick to criticize "mainstream" Egyptologists. In their book The Message of the Sphinx, Graham Hancock and Robert Bauval report on the use of modern technology to investigate the ground surrounding the Sphinx:

In 1973-4 . . . the first in a series of serious pioneering projects was launched, using ground-penetrating radar and other high-tech remote sensing equipment to locate "anomalies" under the bedrock beneath the Sphinx. These projects were channeled through well-established academic institutions - the Ain Shams University in Cairo and the prestigious Stanford Research Institute (SRI) in the USA.
In 1977 the US National Science Foundation funded a project at Giza again involving the SRI. This time use was made of several new techniques such as resistivity measurements (from metal rods driven into the rock across which an electric current was passed), magnetometry, and also the latest aerial photography and thermal infrared image-enhancing techniques. According to the SRI team's official report: "Several anomalies were observed as a result of our resistivity survey at the Sphinx ... Behind the rear paws (north-west end) we ran two traverses. Both traverses indicate an anomaly that could possibly be due to a tunnel aligned north-west to south-east ..." Two other anomalies were noted, deep in the bedrock "in front of the paws of the Sphinx." [p. 90-91]

Hancock and Bauval quote SRI geophysicist Lambert Dolphin, who relayed to me a rather different conclusion in a personal correspondence

Next we drilled 4 inch bore holes on the anomalies and inspected the hole with downhole TV. Nothing was found except small cracks. We paid special attention to the front paws, and under the paws. No chambers!
I do not believe there are any chambers under the Sphinx at this point in time.

There are three known passageways leading into the Sphinx. One is on the back of the Sphinx near its head. This shaft is short and leads to a dead end. Another is at ground level on the north side of the Sphinx near its hip. This shaft has been explored and leads to a dead end below the water table.

Passage entrance near left hip.

The third tunnel is known only from an unpublished photo made in 1926. It is located on the north side near the middle and has been covered with brickwork in later restorations. For more on these tunnels, see Known Sphinx Passages and also Zahi Hawass' 1997 NOVA interview.

Restoration work, 1997.

Zahi Hawass earlier addressed the rumored chamber in his 1990 "Update" to The Pyramids and Temples of Gizah by Flinders Petrie (London: Histories & Mysteries of Man Ltd., 1990; p. 101-102):

The last site investigated by the Japanese [Waseda University in Japan] was the Sanctuary of the Sphinx. The three areas targeted were:

A. South of the Sphinx.
B. North of the Sphinx.
C. In front of the two paws of the Sphinx.

The results were:

A. South of the Sphinx. The Japanese indicated the existence of a hollow 2.5 m. to 3 m. underground. And, they found indications of a groove on the Sphinx body that extends beneath the Sphinx.
B. North of the Sphinx. The Japanese found another groove similar to the southern one which may indicate that maybe there is a tunnel underneath the Sphinx connecting the south and north grooves.
C. In front of the two paws of the Sphinx. The Japanese found another hollow space about 1 m. to 2 m. below surface. Again, they believe that it might extend underneath the Sphinx.

The conclusion of the Japanese work suggests that the sanctuary of the Sphinx contains more cavities below the Sphinx than were previously known.
The combined data collected by the recent research at Giza resulted in the indications that there is/are:

1. Hollows located under the Sphinx as yet, not identified.
2. Cavities running from north to south underneath the Sphinx.
3. A tunnel south of the pyramid of Khufu ...

For more details on the Japanese work cited above, see the Waseda Report highlights.
It appears that there may indeed be undiscovered chambers and/or passageways in the area of the Sphinx. Though the Giza Plateau has been well-excavated, new discoveries are made there each year. But the idea that there is an Atlantean "Hall of Records" hidden under the Sphinx is based solely on the visions of a so-called "prophet" who in 1941 claimed the chamber would be discovered in a "few years."