Two pleasure boats collided on the Amite River in Louisiana, resulting in the death of Clyde Richardson. P sued D alleging that D negligently operated her boat. P claimed jurisdiction under 28 U. S. C. § 1333(1), which gives federal district courts exclusive jurisdiction over '[any] civil case of admiralty or maritime jurisdiction. D moved to dismiss, arguing that the complaint did not state a cause of action within the admiralty jurisdiction because one boat was used for pleasure boating, such as boat riding and water skiing, and at the time of the accident the boat was actually pulling a skier on a zip sled and the other was used exclusively for pleasure fishing and was described as a bass boat. Neither boat had ever been used in any 'commercial maritime activity.' At the time of the accident, neither boat was involved in any 'commercial maritime activity' of any sort. Nothing about the usage of either boat that date smacked of any kind of commercial activity in any manner. The District Court found that there must be some relationship with traditional maritime activity for an injury sustained on navigable water to fall within federal admiralty jurisdiction. It held that commercial maritime activity is necessary to satisfy this relationship, and granted Ds' motion to dismiss the complaint for lack of subject-matter jurisdiction because the collision of these two pleasure boats did not involve any commercial activity. The appeals court reversed. The Court of Appeals agreed that 'admiralty jurisdiction requires more than the occurrence of the tort on navigable waters -- that additionally there must be a significant relationship between the wrong and traditional maritime activity.' Relying on the fact that the 'Rules of the Road' govern all boats on navigable waters, and on the uncertainty that would accompany a finding of no admiralty jurisdiction in this case, the Court of Appeals held that 'two boats, regardless of their intended use, purpose, size, and activity, are engaged in traditional maritime activity when a collision between them occurs on navigable waters.' Ds appealed.