The are two flights each week day to/from Kardla on Hiiumaa to/from Tallinn.
Mon to Fri from Tallinn at 7:45 and 17:45
Mon to Fri from Kardla at 8:45 and 18:45
It is only a 30 minute flight, but probably not recommended for the nervous flyer as it can be bumpy. The planes are only small (about 14 seats). If the weather is bad the flight could be cancelled - the negative being is that the evening flight time is after the last bus!
There are only 4 ferries go from Saaremaa to Hiiumaa. It is important to know timetable. If there is a storm the ferry may be late. Our ferry was late 0,5 hours and we had very emotional way to Hiiumaa. It was storm and ferry shaked very well. Tickets to ferry you'll by in side of ferry.
There are buses each day between Hiiumaa and Tallinn. The bus ticket includes the ferry crossing (stay on the bus until it is on the ferry and return once at Hiiumaa - just follow the crowd).
Buses go to both Kardla and Kaina.
In Tallinn you need the main bus station.
The travel tome is about four and a half hours to Kardla, but can be longer depending on the ferry crossing.
In winter it is possible to drive between Hiiumaa and the mainland, as an Ice Road is created and strictly monitored.
The drive should take about 30mins.
There are obviously rules - for example no seat-belts (easier to escape), not to drive below 40km/h (vibrations not good), no lorries/trucks (bit too heavy).
Despite the worrying rules the Ice Road is a safe and effective winter crossing to Hiiumaa.
The ice road is not open every winter - it depends on the thickness of the ice - in recent years it has not so often been used.
The way to get to Hiiumaa is from the mainland port - Rohuküla (near Haapsalu, about 100 km from Tallinn). The ferry takes about an hour and a half and it is truly cheap. For the passanger that is. But you have to buy a separate ticket for a bike or a car (of course). If you will go by car, it is strongly advisable to book the place at least a week in advance, since the traffic to the island is heavy, especially during the summer. So if you can't book the place, don't go by car. The prot you'll reach on Hiiumaa is called Heltermaa (about 25 km from the main city - Kärdla). During the winter you can cross the see on foot or by car, if the ice-road has been opened.
The easiest way to get there is to use ship. In summer you must bake booking before hand as other ways it might take forever to get there if you go with you own car.