###### Abstract  
A large percentage of the world's population lives along the coastal zones, with more than half of the world's population living in coastal areas. In such a manner, human beings depend on the coasts and oceans for their survival. In more than one way, the coastal areas remain an untapped and untamed resource; however, they are not uninfluenced by humankind. The coastal areas are affected by the urbanization, industrial progress, and the progressive expansion of a society of leisure and crowd tourism. Yet, it is an incomplete view in which an essential element we often forget: the coastal environment. Global climate change may accentuate the social pressure on the latter, namely increases temperatures and sea-level rise. On the other hand, extreme events are more frequent in recent decades. The coastal zone is the limit between the open ocean and the continental interiors, and protect from coastal natural hazards by absorbing energy and momentum fluxes from the ocean. Examples of this are the coastal dunes, beaches, marshlands and diverse bio shields (reefs, seagrass, mangles and other types of coastal vegetation, etc.). A variety of processes, operating at a range of spatial scales, govern the stability of coastal systems. A good example of how it works and the complexity of coastal systems is presented in this Special Issue by [PERSON] et al. [1]. The work analyzes the water circulation in a micro-estuarine environment, in the Ebro Delta in the Mediterranean coast, based on mathematical models. Results show complex dynamics of water circulation due to different processes, including wind forcing mechanisms. Another exemplification is provided by the work of [PERSON] et al. [2] in which research-based on video monitoring systems in South Korea is introduced, intending to prevent erosion by waves in a beach environment. Understanding wave incidence and maritime climate using remote sensing techniques improve the advancement in prediction models of sediment accumulation and erosion cycles. Both works highlight the importance of understanding the natural processes for the correct management and coastal protection. These systems are highly vulnerable to storm-induced hazards, namely coastal erosion and flooding. Combine these with the effect of human activities, which have led to changes in these processes at all spatial scales, resulting in a severe threat for the survival of coastal ecosystems. Indeed, two works in this Special Issue cope with the human-derived impacts. On one side, the work of [PERSON], [PERSON] et al. [3] tackles with conflicting activities within the coast in Vietnam, particularly the Titan mining industry and the use of alternative natural resources and ecosystem preservation. The method used in the evaluation is a combination of Fuzzy AHP and Fuzzy TOPSIS, two analytical techniques to assess conflicting activities. On the other, the work of [PERSON] et al. [4] also assesses environmental impacts due to activities at sea, in a case in point, the dredging and dumping labours, which are a source of pollutants to the marine environment. They approached this problem using meteorological data and mathematical models for pollutant dispersion. Pollution by the dispersion of particles derived from dredging spoils and other sources is another significant cause of concern regarding the impact of human activities on the marine environment. Both pieces of research had stressed how the functionality of the coastal environments could be endangered by one single socio-economic sector, preventing the development of other sources of economy. Moreover, considering that sea-level rise and changes in storminess are linked to climate change scenarios, the increase in risks in these highly populated areas are also expected to rise. In this context, two solutions to hinder coastal erosion are introduced in this Special Issue. First, [PERSON] et al. [5] proposed a method via processes of biocementation, a technique consisting of inducing carbonate precipitation using microbes.