Hearing is of extreme value to marine mammals. They depend on their hearing in every aspect of their life: finding food, mating, communicating with other individuals, escaping the predators, avoiding objects in the sea, and, most importantly, navigation. Noise has many negative impacts on many ecosystems. Still, its most significant negative impact is on the marine environment because the sound travels faster through the water than it does through the air. The considerable increase in underwater noise was detected after the rapid connection of the whole world - the consequence was a rapid increase in the number of ships, oil drilling sites, and other marine activities. The result was a significant increase in underwater noise levels of different frequencies. All of this noise negatively impacts the marine organisms which depend on their hearing. Underwater noise has the most impact on marine mammals. It confuses and disorients them; therefore, they end up washed on the beach and can die. This paper contributes to a better understanding of the impact underwater noise has on the marine environment, focusing on its impact on marine mammals. Also, the paper contributes not only to scientific fields but to educational purposes for the general public, showing major noise problems and their sources while simultaneously proposing alternative ways of managing underwater noise to protect marine mammals and prevent their extinction.