It is estimated that around 70% of the total surface of the earth (approximately 510,072,000 km2), is occupied by various bodies of water, such as seas, rivers, lakes and oceans. They have not yet been fully explored, so most of the species, both flora and fauna, remain unknown; however, a large amount of data has been collected on how the maritime ecosystem develops. In addition to this, studies have been carried out on the shallower areas of the seas and oceans, including the coasts.
"Coast" is used to talk about the portions of land that border the seas or oceans, as well as the islands scattered around the planet. Generally, they are defined as an unstable landscape, due to the constant changes that the soils undergo, due to the action of maritime erosion and sedimentary deposits, which subtract or add sand to certain places, as well as the waves, the climate and the human activities. It is from these that the beaches originate, characterized by deposits caused by recurring waves, which can be fine sand, or boulders.
Despite this, some coasts have certain characteristics that are very attractive to tourists. These are caused by various geographical accidents, which can turn them into bays, gulfs, headlands, among others. Other modifications, as mentioned above, can be presented by human hands, such as the construction of containment walls to prevent flooding. Even so, this only happens when coasts turn out to be areas prone to strong waves.
