Bay of Bengal is located between latitudes 5°N and 22°N and longitudes 80°E and 100°E. The Bay occupies an area of about 2.2 million sq km, the average depth is 2,600m with a maximum depth of 5,258m and the Bay is about 2,090 km long and 1,610 km wide and is bordered on the South in the West by Sri Lanka and India, on the North by Bangladesh, and on the East by Myanmar and Thailand. It is also a primary source of water access to Bangladesh and Myanmar. The surface hydrology of the Bay of Bengal is basically determined by the monsoon winds and to some extent by the hydrological characteristics of the open part of the Indian Ocean. In this book, an effort was made to describe the physic chemical characteristics of water in the Bay of Bengal using the data of physical and chemical parameters.