Marine experts have discovered a clump of archaeological structures deep beneath the sea off India's western coast. Although the discovery has not yet been accurately dated, the structures are said to resemble archeological sites belonging to the Harappan civilisation, dating back more than 4,000 years. This is the first time man-made structures have been found in this part of the Arabian Sea which is known as the Gulf of Cambay. The images gathered over the past six months led to a surprising discovery - a series of well-defined geometric formations were clearly seen, spread irregularly across a nine-kilometre (five-mile) stretch, a little beneath the sea bed. Some of them closely resemble an acropolis - or great bath - known to be characteristic of the Harappan civilisation. A leading marine archaologist says that far more detailed investigations need to be done to confirm the exact date of the structures.