A group of treasure hunters made international news in February 2012 after claiming they’d found billions of dollars in sunken treasure off the coast of Cape Cod, Massachusetts. The cargo of the S.S. Port Nicholson, which was torpedoed by German U-boats during World War II, includes tons of platinum, uncut and industrial diamonds and gold ingots. It may turn out to be the most lucrative shipwreck ever found in U.S. waters. In the days long before electronic bank transfers, ships frequently transported staggering amounts of gold and other precious metals. Many were lost at sea, but thanks to modern technology, finds of sunken treasure have become increasingly common in recent years. Here are five of the most valuable shipwrecks discovered in U.S. waters prior to the S.S. Port Nicholson.