Fiordland’s has ten marine reserves, spanning from Milford Sound in the north to Preservation Inlet in the south.The water in Fiordland is as unique as the acclaimed landscape above. Runoff from heavy rainfall on the mountains creates a permanent fresh water layer on the surface of the salt water. This varies in depth from 5 centimetres to over 10 metres.The reserves include a huge variety of habitats and species. There are sponges, lampshells and a wide range of fish. The area also has some of the world's largest black coral trees – some over 300 years old – which have brittlestars entwined in their branches. The fiords are also home to brachiopods - clam-like animals that have remained relatively unchanged for over 300 million years.Bottlenose dolphins (aihe), New Zealand fur seals (kekeno), Fiordland crested penguins (tawaki) and little blue penguins (korora) are resident in the fiords.Scuba diving is the best way to appreciate the submarine wonders of Fiordland, and there are several operators who can take you on a guided scuba expedition. There is also an underwater observatory in Milford Sound, situated in the middle of the Piopiotahi Marine Reserve.