To reach Nisyros by plane one can land at Kos international airport ‘Hyppocratis’ (KGS) or at Rhodes international airport ‘Diagoras’ (RHO), with some particularities that I explain below.
Kos airport
The airport of Kos, is a seasonal airport with flights to and from many European cities, while it remains active for flights to and from Athens all year round.
It is relatively far from the town centre (about 25 km) from where you can catch the Blue Star Ferries and the Panagia Spiliani ferry, but it is close to the port of Kardamena, which, in summer, is served daily by tourist ferries that leave at 09.00 and return at 19.00 at the latest, taking about 45 minutes.
Here the bus timetables to and from the airport and main ports:
From the port of Kos town to get to Nisyros one can arrange to take the Blue Star ferry that runs every Monday morning around 01.00 or Friday morning around 02.00. From the port of Nisyros the departure is on Monday evening at around 20.00 and on Friday at 23.30.
While the Panagia Evaggelistria ferry departs from the port of Kos on Monday, Tuesday, Thursday and Friday at 2.30 p.m., arriving in Nisyros at 5.30 p.m. after about a two-hour journey. From Nisyros the departure follows the same pattern with departure at 07.00 and arrival at the port of Kos at 09.45.
In addition one can opt for the fast catamaran Dodekanisos Seaways Pride on Tuesdays and Wednesdays at 16.00 with arrival at the port of Mandraki Nisyros at 16.50 after about 50 minutes. While from Nisyros the ferry departs at 10.45am also on Tuesdays and Wednesdays.
Rhodes Airport
The island of Rhodes, being the capital of the region, is better served, although mainly the same rules apply as for Kos; it is also a seasonal airport, and should be considered for summer flights with the main low-cost airlines, while in the other months it can be reached by stopovers to and from Athens with the national airlines Aegean and Olympic, and the private SkyExpress.
From the airport the bus connections are continuous and the journey takes about 45 minutes from the city centre.
The main ferries are the Blue Star ferries on Monday afternoons at 16.00 and Friday afternoons at 19.00, the journey time is about 4 hours, and especially in the summer you can enjoy the ferry ride through Symi and Tilos skimming the coasts of Turkey. Arriving at the port of Mandraki at 20.00 and 23.30 respectively and then continue towards Kos with final destination Athens passing through some intermediate islands
In addition, the fast catamaran Dodekanisos Seaways “Pride” departs from Rhodes port “Kolonas” at 08.30 on Tuesday and Wednesday and arrives at Mandraki Nisyros port at 10.45 and then continue towards Kos-Kalymnos-Astypaleia.
Other travel possibillity exists but are too much imprevedible to be planned correctly.