A Group on a boat trip on a Swiss lake c1960

A high quality picture of a family or group of friends on a boat trip in about 1960.

This is another medium format slide taken on good quality colour slide film which has resulted in brilliant picture quality. When you look at this picture it's difficult to believe it was taken over half a century ago.

It shows a group of four who are obviously enjoying a boat trip on what I suspect is one of the lakes in Switzerland. It looks as though the couple at the end are married, or at least the girl is wearing a wedding ring, and I believe the person taking the picture will be the other man in this group, who has been in some of the other pictures. The one improvement which could have been made would have been to remove the shadow over the middle lady's face - mind you it's a bit late to do that now!

I'm interested in the device behind the group, which seems to be a mouthpiece for giving instructions. I wonder when that was used since this seems to be a passenger area of the boat? Perhaps I've misinterpreted what it is.