A few kilometers from the shores of Palm Beach County, Florida, is the Gulf Stream current--a remarkable "river" within an ocean. The current's journey across the Atlantic Ocean connects southeast Florida and southwest Great Britain as it streams steadily north at speeds of 97 km a day; moving 100 times as much water as all the rivers on Earth. The author uses the 5E constructivist instructional model--Engage, Explore, Explain, Elaborate and Evaluate--to analyze a single problem: why the iceberg that sank the "Titanic" neither dissolved nor deflected eastward by the Gulf Stream before the collision. (Contains 7 figures.)