Currently almost every seaside country in the world is affected by Harmful Algal Blooms (HABs), commonly called" red tides". This diverse array of phenomena includes blooms of toxic, microscopic algae that lead to illness and death in humans, fish, seabirds, marine mammals and other oceanic life forms. There are also non-toxic HABs that cause damage to ecosystems, fisheries resources and recreational facilities. It is responsible for economic losses in coastal states. The aim of this study is analyze what is the HABs from the Qur'anic viewpoint and modern marine science as well as detect why appears such a disaster in costal and what is its solve from the Qur'anic standpoint. As a result, the study found that the Holy Qur'an has mentioned (al-fasad) disasters to refer to numerous kinds of calamities, contaminations and pollutions in sea including the HABs. Also, it included historical, current and whatever new form of disaster will appear in future both in land and sea. As a cause for the HABs the study found Almighty Allah mentioned cause and 2 purposes for HABs in the sea: HABs are reaction of humans' wrongdoing; HABs are to give punishment the Humans for their immoral actions; HABs are to return to the right way. Similarly, it found integration between the Qur'anic viewpoint and modern marine science in HABs that" Humans' activities profoundly affect the amount of fresh water which reaches the coast, and this can enhance HABs".