The very nature of these warships is what makes them both so difficult to remove from the ocean floor and so appealing to illegal salvagers ballsy enough to try. Consider this: The Perch, which was as long as a football field and 26 feet wide, displaced nearly 2,000 tons when submerged. The Encounter and Exeter belonged to a robust class of British destroyers that carried torpedoes, anti-aircraft weaponry, and a complement of about 150 sailors each. The De Ruyter was the largest of all, with a length of more than 560 feet. All now gone without a trace. ... Even in poor condition, gleaned steel fetches about $150 a ton in international markets. A recovered destroyer can easily result in a profit of $100,000 ... There’s a ton more money to be had if you find ships built before the dawn of nuclear testing. Steel is made by melting iron at super-high temperatures and infusing it with carbon. To make sure those carbon levels don’t get too high, steelmakers blow oxygen into the mix, along with ambient atmospheric particulates. That includes radiation. Natural elements like radon create low-level natural radioactivity. We increased those levels exponentially when countries like the United States and Russia began nuclear testing in the mid-1940s. France, England, and China jumped on the bomb bandwagon a few years later. And with each detonation, radioactivity levels in our atmosphere increased. That meant each time steelmakers were blowing oxygen into new steel, they were also blowing nuclear particulates into it. ... That’s not true for the steel used to fabricate pre-1942 vessels, which is virtually radiation-free. And its clean status makes this metal particularly valuable for some technical applications of nuclear medicine and, more commonly, the development of nuclear energy and weapons.