It is still allowed for everyone to go on a cruise to Åland r/t without getting off on Åland. To enter on Åland, the following applies: On September 24th, the Government of Finland decided on entry restrictions, which will take effect on Monday September, 28. The entry restrictions will then be reintroduced in the traffic between Sweden and Åland/Finland. You can still travel to Åland/Finland from Sweden for special reasons, read mor here (see header:5.2 Interpretation guidelines: restriction category 1) You can now travel to Åland/Finland to work without the need of voluntary quarantine for 7 days.
Information from the Åland Government regarding what is required when entering Åland, see regeringen.ax/coronaviruset-covid-19 and Finnish border guard's current rules at raja.fi/current_issues/guidelines_for_border_traffic
It is the traveler's own responsibility to familiarize themselves with the recommendations of the authorities and the hygiene and health rules that the authorities have introduced.