Congress passed sweeping laws after the Exxon spill, which forced the oil industry to invest in spill prevention and clean-up preparedness. These efforts have paid off: the number of tanker spills is dramatically lower today. We climb aboard a tanker and head to sea to examine how alcohol testing and updated navigation technology make these ships safer. However, some of the new tanker regulations do not apply to ports outside Alaska. And scientists are worried about a growing threat — oil spills from freighters, barges, and vessels other than tankers.