Fredriksen made his fortune during the Iran-Iraq wars in the 1980s, when his tankers picked up oil at great risk and huge profits. As described by his biographer, "he was the lifeline to the Ayatollah." Fredriksen would later become the world's largest tanker owner, with more than seventy oil tankers and major interests in oil rigs and fish farming. His fleet is dominated by costly double-hulled, environmentally safer tankers.