The tanker, owned by a Liberian-registered company and flying a Bahamas flag of convenience, was still carrying some 67,000 tons of heavy fuel oil in its hold compartments when it split in two on Tuesday and dived down more than 3.5 kilometers to the depths of the ocean. The spill threatens the region's economic and environmental well-being, which is largely dependent on the sea for its livelihood. Spain has warned that the eight-kilometer slick, propelled by strong southwesterly winds, was headed toward the Galician coast.