A tsunami, caused by an earthquake in the Tyrrhenian Sea, devastates Naples and the Maritime Republic of Amalfi, among other places.

A tsunami is a series of waves in a water body caused by the displacement of a large volume of water, generally in an ocean or a large lake. Earthquakes, volcanic eruptions and underwater explosions above or below water all have the potential to generate a tsunami. Unlike normal ocean waves, which are generated by wind, or tides, which are in turn generated by the gravitational pull of the Moon and the Sun, a tsunami is generated by the displacement of water from a large event.

The 1343 tsunami struck the Tyrrhenian Sea and Bay of Naples on 25 November 1343. Underground shocks were felt in Naples and caused significant damage and loss of lives. Of major note was a tsunami created by the earthquake which destroyed many ships in Naples and destroyed many ports along the Amalfi Coast including Amalfi itself. The effects of the tsunami were observed by the poet Petrarch, whose ship was forced to return to port, and recorded in the fifth book of his Epistolae familiares. A 2019 study attributes the event to a massive submarine landslide, caused by flank collapse of the Stromboli volcano.

The Tyrrhenian Sea is part of the Mediterranean Sea off the western coast of Italy. It is named for the Tyrrhenian people identified with the Etruscans of Italy.

Naples is the regional capital of Campania and the third-largest city of Italy, after Rome and Milan, with a population of 908,082 within the city's administrative limits as of 2025, while its province-level municipality is the third most populous metropolitan city in Italy with a population of 2,958,410 residents, and the eighth most populous in the European Union. Its metropolitan area stretches beyond the boundaries of the city wall for approximately 30 kilometres. Naples also plays a key role in international diplomacy, since it is home to NATO's Allied Joint Force Command Naples and the Parliamentary Assembly of the Mediterranean.