A massive spill of an unknown substance has been detected in the Baltic Sea, off the coast of Sweden. According to the Swedish Coast Guard, who detected the spill on June 8, the affected surface area is 77 km2 (30 mi2) and is located in both Swedish and Finnish waters. “What the spill consists of is still not clear but it is not mineral oil, and there is currently no immediate threat of landfall,” the coast guard said. It said it had mapped the spill using planes and also collected samples, adding that it would not be able to comment...