Deep-sea treasure hunters and commercial salvage teams face a formidable legal barrier when encountering historical naval shipwrecks: the Sunken Military Craft Act (SMCA) of 2004. Enacted by the United States, the SMCA codifies the international legal principle of sovereign immunity, establishing that government-owned vessels and aircraft remain the permanent property of their flag nation, regardless of how much time has passed or where they rest. Under the law, military shipwrecks are treated as active military property and sacred war graves, prohibiting unauthorized disturbance, salvage, or excavation.
However, significant legal loopholes and geopolitical tensions complicate the enforcement of these protections. The SMCA primarily exerts jurisdiction over US craft worldwide and foreign military craft resting within US territorial waters. In international waters, enforcing protections against illicit salvage operators requires robust bilateral treaties and active international cooperation.
Illicit scrap metal salvagers have used non-metallic dredging equipment to secretly demolish WWII wrecks in Southeast Asia for valuable low-background steel—steel produced before nuclear testing. Furthermore, sovereign immunity claims can clash with local territorial claims when a ship sank in waters currently claimed by another country, creating intense diplomatic friction over who possesses final authority over the deep-sea military remains.