Tickets has to be purchased in advanced via Hanko Lines webshop; there is a limited amount of passengers and bicycles taken on the boat! Note that even though children under the age of 5 can join the trip for free, they also have to be included in the reservation.
The timeline between the different locations is presented as longer (approximately 5-20 minutes) than the trips actually take, so it is possible to leave the boat for a quick stroll.
Only 1 handbag/bag/backpack per passenger!
Note that the boat is not disabled-accessible, unfortunately.