Visitors to Fiordland are mesmerized by the enormous lush cliffs – etched with waterfalls – and the mountain peaks defining the U-shaped valleys. Sure, tourists love being on the water. Yet they do not study it unless hoping to see some of the 70 bottlenose dolphins resident in Doubtful Sound. People assume this is saltwater because it connects with the Tasman Sea. Surprisingly, the ecosystem is a mix of aquatic and marine. As far as 30 feet below the surface is freshwater. The low salinity is caused by the region’s extensive rainfall. The water color is a murky brown because of plant tannins draining from the forest. Below 30 feet is dense, dark saltwater that is not conducive to much life.
