thumb|upright=1.25|Global sea levels during the [[Last Glacial Period|Last Ice Age (South Asia)]]
Marine Archeology in the Gulf of Khambhat - earlier known as Gulf of Cambay - centers around controversial findings made in December 2000 by the National Institute of Ocean Technology (NIOT) under the Gulf of Khambhat, a bay on the Arabian Sea on the west coast of India. The structures and artifacts discovered by NIOT are the subject of contention. The major disputes surrounding the Gulf of Khambhat Cultural Complex (GKCC) are claims about the existence of submerged city-like structures, the difficulty associating dated artifacts with the site itself, and disputes about whether stone artifacts recovered at the site are actually geofacts or artifacts. One major complaint is that artifacts at the site were recovered by dredging, instead of being recovered during a controlled archeological excavation. This leads archeologists to claim that these artifacts cannot be definitively tied to the site. Because of this problem, prominent archeologists reject a piece of wood that was recovered by dredging and dated to 7500 BC as having any significance in dating the site. The surveys were followed up in the following years and two palaeo channels of old rivers were discovered in the middle of the Khambhat area under water depths, at a distance of about from the present day coast.
Initial discovery
right|thumb|upright=1.35|Gulf of Khambhat on the right. Image [[NASA Earth Observatory]]
On 19 May 2001, India's Union Minister for Human Resource Development, Science and Technology division, Murli Manohar Joshi, announced that the ruins of an ancient civilization had been discovered off the coast of Gujarat, in the Gulf of Khambhat. The site was discovered by NIOT while they performed routine pollution studies using sonar, and was described as an area of regularly spaced geometric structures. It is located from the Gujarat coast, spans , and can be found at a depth of . In his announcement, Joshi represented the site as an urban settlement that pre-dates the Indus Valley civilization. However it was later on 22 May, reported that the discovery has not been dated and the discovery (for example, great baths) resembles the Harappan civilization dating 4,000 years ago. Furthermore, the Indus civilization port Lothal is located at the head, Gulf of Khambhat.
Follow-up excavations
A follow-up investigation was conducted by NIOT in November 2001, which included dredging to recover artifacts and sonar scans to detect structures. Among the artifacts recovered were a piece of wood, pottery shards, weathered stones initially described as hand tools, fossilized bones, and a tooth. Artifacts were sent to the National Geophysical Research Institute (NGRI) in Hyderabad, India, the Birbal Sahni Institute of Paleobotany (BSIP) in Lucknow, India, and the Physical Research Laboratory in Ahmedabad, India. The piece of wood was carbon dated to an age of 9,500 years old.
Artifacts
Another controversial issue are the artifacts retrieved from the site during the various excavations. It is disputed that many of the items that have been identified as artifacts by the NIOT investigators are actually man-made. Instead their artificial nature is contested and they are argued to be stones of natural origin.