Introduction

About 4600 million years ago, the planet Earth arose from a mass of dust and gases derived from the formation of the star we know as the sun. Initially a dry planet, water began to accumulate in its atmosphere as it cooled. The initial mass of water grew due to the contribution of ice derived from comet impacts and other internal processes that increased the volume of water on the Earth’s surface until it formed the oceans, which currently cover three quarters of our planet containing 97.2% of the water, giving it its characteristic bluish colour when observed from space (Fig. 1.1), which differentiates it from any other plant in the known universe and which led the science fiction author Arthur C. Clarke to affirm “How inadequate is call the planet Earth, when in reality it is Ocean”.