By car: from Tallinn the journey is around 4 hours in total, including 30 minutes on the ferry. You can book your ferry crossing in advance https://www.praamid.ee/wp/?lang=en

By coach: from Tallinn, a 4 hour journey including 30 minutes on the ferry

By air: 20 seater flights operate twice per day from Tallinn, flight time is 30 minutes. http://www.kuressaare-airport.ee/eng/info/airlinesatkuressaareairport