A conference at Sands Hotell already begins with the boat trip to Sandhamn. There are regular archipelago ferries from Stavsnäs to Sandhamn every day, the year around. During the summer months you can even go from Strandvägen in the centre of Stockholm. It takes about half an our in a taxi boat from Stavsnäs.
If you want a real “speed experience” you can rent a RIB-boat or a former Navy Attack boat and get from Stockholm to Sandhamn in just under an hour and a quarter.