Milford Underwater Observatory

Run by Southern Discoveries, this small observatory is NZ's only floating underwater observatory, with displays on the unique natural environment of the fiord. The centre offers a chance to view corals, tube anemones and bottom-dwelling sea perch from 10m below the waterline. It's only accessible on a cruise by any of the operators – some include a visit (such as Southern Discoveries' Scenic Cruise, from $90/55 per adult/child), others offer it as an add-on; check when you book.