common tuatara (Sphenodon punctatus)

September 2012, Tiritiri Matangi island, Auckland

A young animal with some regrowth of the tail (they can drop their tails in the same way that a lizard can).

Is this the only place that tuataras can be seen in the wild with any regularity?

Not the only place, but one of the few that is easily accessible. They are only on islands now (apart for some on fenced mainland sanctuaries) and most islands require permits to visit. If you can arrange to visit them, then Tuatara would be easy enough to see.

Tiritiri Matangi, where this photo was taken, is open to anybody and there are daily ferries from Auckland. And there are Brothers Island Tuatara on Somes Island in Wellington Harbour which is just as easy to visit. Those are probably the two most convenient locations for your average person.