Abstract: “Marine Gravity Waves (tsunamis) are a secondary geodynamic phenomenon caused mainly after large undersea earthquakes and characterized by a series of huge, gigantic waves. However, this phenomenon may also be caused by a number of other causes such as a volcanic eruption, an undersea landslide, even a nuclear weapon testing explosion and extraterrestrial causes (meteorites or asteroids). Due to the low appearance frequency, the risk of a potential disaster a tsunami can cause is often underestimated. The aim of this paper is the study of tsunami waves in Greece and particularly in Maliakos (or Malian) Gulf. The study of tsunamis allows a better understanding of their importance as natural phenomena and the effects that they can cause at the coastal zone. The results of the research show that the area has been hit by a forceful tsunami at least once in the past, according to historical data and analyses of samples from the area, and due to the seismicity of the entire Hellenic area, the”

Keywords: Maliakos (Malian) Gulf, Fthiotida, Seismic Sea Waves, Marine Gravity Waves