With a tidal range of nearly 50 feet, the Bay of Fundy has the highest tides in the world. Twice a day, vast areas of the seafloor are uncovered at low tide, revealing large sand bars, mud flats, and even ancient forests drowned by the rise of the sea. Tidal action mixes the ocean water and makes the entire nearshore system highly productive. As a result, whales — including the endangered North Atlantic right whale — migrate to feed on the bounty of zooplankton in the mouth of the Bay. In the upper reaches of the Bay of Fundy at low tide, many species of migratory birds " up" prior to their long southerly migrations by consuming large quantities of tidal-flat animals, like sea fleas and mud shrimp. The cool, nutrient-rich, tidally-mixed water then flows from bay along downeast Maine coast, creating a unique, foggy microclimate and increasing fertility of waters to the southwest.