The archipelagos are all fairly flat and small, but are still ideal for cycling tours. Ferries run between the archipelago. However, you should familiarise yourself with the timetables beforehand and possibly even reserve a place for yourself and your bike in the summer months.
The islands are numerous, flat and mostly small. Car traffic is limited.
Åland-Round 252 km, easy
Mariehamn - Lemland - Lumparland - Seglinge - Kumlinge - Vårdö - Prästö - Sund - Saltvik - Tjudö - Isaksö - Skarpnatö - Hammarland - Eckerö - Tsarens - Torp - Mariehamn.
Ferries and flights from Stockholm, Turku and Helsinki, among others. In June, July and August there are several bicycle ferries (tel. 00358-18-37 227 and 00358-400-229 149) between some islands, otherwise regular archipelago ferries from Alandstrafiken, which you should book in advance to be on the safe side in the high season.
Best time to travel Mid-June to the end of August
Addresses under http://www.visitaland.com/de
Bike hire and service are mainly available in Mariehamn.
Nordic Holidays http://www.nordic-holidays.de
Maps "Ahvenanmaa Turun Saaristo" Åland Islands 1:100,000 for approx. 20 euros.
Edition Elch "Finland: Aland Islands", 288 pages, 18.90 euros.