Preface

According to The UNESCO convention on the protection of underwater cultural heritage 2001, there are an estimated more than three million undiscovered shipwrecks lying on the ocean floor. The Dictionary of disasters at sea also mentions that approximately 12,542 sailing ships and war vessels were lost at sea between 1824 and 1962 CE. Successful voyages of wind driven cargo ships across the seas were governed by a thorough knowledge of the intensity, strength and directional changes in the monsoon winds blowing over the oceans, in particular the Indian Ocean and the Mediterranean east. Cyclonic storms which are common to the Indian monsoon circulation during the summer and winter months were also a major hazard to be negotiated by the voyagers. Other factors such as knowledge of bathymetry along the sea route, sand and laterite ridges on the continental shelf and periodic earth movements are vital for successful voyaging in the Indian Ocean region. The trade winds blowing from the equatorial west Pacific facilitated the movement of trading ships from Southeast Asia to India and further west. Similarly, the winter easterlies from the Mediterranean favoured the Red Sea voyagers and movement of ships towards India. The north-east monsoon was also favourable for the Indian ships bound to Southeast Asia.