A massive stockpile of explosives, estimated at approximately one million tons, lies submerged in the Casquets Trench, also known as Hurd's Deep, located between French and British waters. This site contains munitions accumulated over more than a century, along with radioactive waste and the wreck of the German battleship SMS Baden, which was deliberately scuttled in 1921. The trench is situated off the coast of the Cotentin, west of the Casquets islets, about thirteen kilometers northwest of Aurigny, extending between 100 and 160 meters below sea level. The geographical position of the trench, straddling the waters of the bailiwick of Guernsey and the French exclusive economic zone, has contributed to the issue being largely overlooked by both jurisdictions. The practice of submerging munitions began after World War I when the British government sought to dispose of surplus chemical and conventional munitions by using the isolated and deep Casquets Trench as a natural dump. This practice continued after World War II, when it became necessary to dispose of weapons and munitions abandoned by German troops expelled from the Anglo-Norman islands. Between 1950 and 1963, the United Kingdom added no fewer than 28,500 barrels of weakly and moderately radioactive waste, totaling between 14,000 and 17,000 tons, to the site. France has also used various methods to dispose of its munitions since the 1920s, including immersion by air, submarine, or boat in less frequented areas such as the Levi Cap trench or the Casquets trench. The French Navy significantly reduced these practices from 1998, with the annual volume of submerged explosive material dropping below ten tons per year until the last recorded operations in 2002. The corrosion of metal casings of the munitions has led to pollution incidents, such as the loss of containers of lindane and pesticides. In December 1993, a five-ton container of lindane was lost, and in another incident, the container ship Sherbo released 90 containers, ten of which were loaded with pesticides. These incidents, combined with the slow natural degradation of historical munitions, create a chemical cocktail whose evolution remains difficult to predict. The OSPAR Commission, responsible for protecting the North-East Atlantic marine environment, has recorded 148 underwater landfills in this region, 62 of them off the French coast. Despite the presence of such a large volume of munitions, no major cleanup operations are being considered. Raising munitions several decades old, corroded and potentially unstable, represents a significant risk for anyone attempting to do so. The mere act of handling these devices could cause explosions or leaks of toxic substances even more dangerous than their continued presence at the bottom of the water. The question of cost and legal responsibility further complicates the situation, as the trench crosses British and French waters, making it difficult for either authority to shoulder the burden of such a colossal project. As a result, the status quo persists, with monitoring being the only current response to this issue.