Why century-old naval mines remain dangerous

Can old naval mines still wash ashore and explode today?

Yes; mines can survive for many decades in favorable salt-water conditions, and newly floating examples are particularly difficult to render safe.

Long immersion does not guarantee that a naval mine is inert. Mines associated with the 1904-1905 Russo-Japanese War reportedly washed ashore in China more than a century later. Salt water can preserve explosives and mechanisms when the surrounding conditions are favorable. A weapon that has rested deep or buried may become especially unpredictable when it breaks free and begins to move. Modern authorities must therefore treat newly floating or beached mines as live ordnance until specialists prove otherwise.