A large explosion of ammonium nitrate stored at the Port of Beirut in Lebanon killed 218 people and caused US$15 billion in damage.

On 4 August 2020, a major explosion occurred in Beirut, Lebanon, triggered by the ignition of 2,750 tonnes of ammonium nitrate. The chemical, confiscated in 2014 from the cargo ship MV Rhosus and stored at the Port of Beirut without adequate safety measures for six years, detonated after a fire broke out in a nearby warehouse. The explosion resulted in at least 218 fatalities, 7,000 injuries, and approximately 300,000 displaced individuals, alongside property damage estimated at US$15 billion. The blast released energy comparable to 1.1 kilotons of TNT, ranking it among the most powerful non-nuclear explosions ever recorded and the largest single detonation of ammonium nitrate.

Ammonium nitrate is a chemical compound with the formula NH₄NO₃. It is a white crystalline salt consisting of ions of ammonium and nitrate. It is highly soluble in water and hygroscopic as a solid, but does not form hydrates. It is predominantly used in agriculture as a high-nitrogen fertilizer.

The Port of Beirut is the main port in Lebanon on the eastern part of the Saint George Bay on Beirut's northern Mediterranean coast, west of the Beirut River. It is one of the largest and busiest ports on the Eastern Mediterranean.