Hire a boat and skipper for your group's own use. Departure from Taalintehta.
Go sightseeing, geocaching, exploring the archipelago sea, diving or fishing as a group. The skipper has a coastal boatman's certificate, extensive local knowledge, first aid 1 and 2 and a fishing and wilderness guide's certificate.
So you're in safe hands.
Kippari is also into geocaching himself, so you can ask him for tips on that too!