Nisyros, with fewer than 1000 permanent inhabitants, is famous for having the only 'active' volcano in Greece together with Santorini (Thyra). The island is essentially a volcanic cone with a large collapsed caldera in the center. It is possible to walk into the volcanic crater and view the smoking fumaroles at close hand.
There are two main villages on the island; Mandraki in the north-west (where the ferries dock) and Nikia, up on the edge of the volcanic rim to the south. In Nikia the people are not Nisirians, they are Nikiates. They inhabited Nisyros hunted from pirates and settled there around 1600. Still today, when asked, they never say "I am from Nisyros" they say "I am from Nikia".
Nisyros is one of the stops for ferries that run between Piraeus (on the Greek mainland) and Rhodes, with other nearby stops being at Kos, Tilos and Symi. Sailings are not to a regular daily schedule and become less frequent in the winter months.
In addition, a fast catamaran service runs to Rhodes on some days (via Tilos), and many tourist boats bring day-trippers over from Kos each morning, returning early afternoon.
Mandraki and Nikea are small enough to stroll around on foot. To travel between the two there is an occasional bus service, or you can take a taxi. Alternatively, it is a half day hike between the two villages, via the volcanic crater. There is one car and motorcycle rental based on the main port.
The walk in volcanic crater. A path leads down to the yellow, sulfur-stained floor where you can walk up to and view the steaming vents.
Hike between Nikea and Mandraki via the volcanic crater. Most hotels on the island have free maps available for anyone interested in walks around the island.
If you go to Nisyros with a group, try to avoid where the tour guide sends you to eat. Some tour guides get a commission from the restaurants, which means it will be expensive. Look around and try to avoid the main tourist pathways.
There are a few hotels at the harbor in Mandraki. Prices from around 30 euros. In Loutra (about 1.5 km from the harbor, there's a hotel at the hot baths, where rooms can be rented for 20 euros (basic and clean, toilet/bath shared), single rooms 17 euros (prices July 2013). The hotel is situated on the left, coming from Mandraki. It's a big white building. Great atmosphere!