We had booked the boat trip as part of a day trip to the Green Canyon and had lunch in the "Green Canyon" restaurant and then on the catamaran.
The lunch buffet was bad because it was cold, there was hardly any choice, too many people for too few pans, no knives, etc.
The boat trip itself offers wonderful impressions, lasts about 90 minutes and goes about 5-7 km across the lake and into the gorge. Swimming break (about 30 minutes) on a platform included. Changing facilities available.