Ios is a relatively easy island to get to - much better than it used to be, which is why it has always been more of a 'hidden secret' and has retained a much more understated reputation and is less developed than some of it's neighbours.
FLIGHTS
For the best deals from the UK, check out Easyjet, Thomson, First Choice or Avro online.
Obviously book as early as possible with Easyjet (flights for Summer 2010 to Santorini go on sale in 24th October 2009) and Thomson often has some last minute bargains, but again, better to get booked early.
You can also find details of which low-cost airlines fly from which European cities to Santorini (and their respective website links) at:-
http://www.low-cost-airline-guide.com/en/cheap_flights_to_Santorini.htm
or to Athens
http://www.low-cost-airline-guide.com/en/cheap flights to Athens.htm
You could also fly internationally to either Mykonos, or Crete.
FERRIES
Ios is a well-connected hub, visited by many ferry companies daily. Approximate journey times via the new high speed comfortable catamarans are as follows:-
Santorini 30 minutes Naxos 1 hour Paros 1.5 hours Mykonos 2 hours Crete 2.5 hours Athens 4.5 hours
From Santorini
From Santorini airport, get a taxi (approx 20 euros) to the port, 20 minutes drive away. Public buses also run, via the main town.
From the port, catch a ferry. The high-speed catamarans take approximately 30 minutes. For ferry times, please Use this link for Santorini Ios ferries and once aboard, watch out for the dolphins along the way!
Athens to Ios
When you arrive in Athens airport, make your way to Piraeus (ferry port) from where the ferries leave. There are a number of options from the airport: metro (approx 1 hour 30 mins), the bus, (approx 1 hour 30 mins, depending on traffic) or taxi (roughly 30 - 40 euros).
There are a number of ferries from Athens to Ios. Take the fast Catamaran and you'll arrive in around 4 hours, or take the slow boat sit back relax, tan on the deck and it'll take 8 - 12 hours. Use this link for Athens Ios ferries.