The Doubtful Sound is so named because Captain Cook observed it from see with doubt that he could ever sail back out.  Must have had a bum diesel auxiliary in his old tub.  If he would have entered he would also have discovered that the anchoring was pretty deep as well. 

The Doubtful Sound is the largest of the sounds of Fjordland and it is several times bigger than the more visited Milford Sound.  It is not accessible by road though it is possible to put a car on a ferry across Lake Manopouri and then drive over a low pass and down to the sound on a well maintained gravel road.

This being more effort than most tourists would want to attempt means that most people visit the sound on the Doubtful Sound Tour offered by Fjordland Travel.   The first part of the tour is described in the Lakes of Fjordland page.

Upon arrival at the summit of the pass you are greeted with a spectacular view of the inner sound.  It becomes obvious that Captain Cook was right, it would not be easy to sail in these deep canyons.

Once you are down to the sound you board a fast catamaran to tour the sound all the way out to the Tasman sea.  The views are constantly changing and each is spectacular.  It would be great to cruise the sound but it wouldn't be easy to get put away at night.  There are not a lot of good anchorages but it is possible to pull into a narrow canyon and tie off to trees or rocks on either side.

The mountain sides are granite with very little top soil.  The plants and trees get a pretty weak hold but they interlock roots and manage to hang on.  A pretty common occurrence is a tree slide.  When a tree falls it ends up bringing a whole hillside of vegetation along with it.  These scars are clearly visible on the hillsides and they are slow to heal.  This is a normal part of the regeneration of the forest.

Wildlife abounds in the sound.  Seals are plentiful on the rock on the outside of the sound.  They haven't been hunted for many years so they are undisturbed by the close pass the ferry makes.  Further inside the sound lives a pod of dolphins.  They remain in the sound all year round.  They also seem unbothered by the ferry but the younger members have discovered that the wake makes for a good launching pad for aerial acrobatics.  As they spend their whole lives in a calm sound they don't get much exposure to waves and they take full advantage.  As the ferry goes by the dolphins swim into the wake and then launch themselves 5 to 10 feet in the air.  The ferry makes several passes so dolphins and humans both get there fill.