Every Monday you can get a dayticket for Thunersee and Brienzersee for just 25 sfr (1st class is 35 sfr).
This ticket will include all of the cruises, BUT NO trains ! So you would have to pay a seperate fee of 2,20 sfr for the train between Interlaken Ost and Interlaken West ( the conductor will NOT check the tickets for that ride of just 3 minutes !! )
25 sfr for the 2nd class - that is all of the lower deck of the ships
35 sfr for 1st class - all of the upper decks with better views and mostly also less crowded than 2nd class.
Both classes have their own, seperate restaurants
