This was the only tour activity we signed up for - Zambezi River Sunset Cruise. We went with the tour that the hostel offered, at USD 50 per person. We were picked up from the hostel and paid to the staff in the pick up van. There were probably about 20+ pax. On the boat, there were tables and a few chairs to each table. We were among the last ones to get on the boat and were seated with 3 other people. 2 were friends and another one was travelling by himself.
The first animal we saw was an elephant.
Then we saw some hippos' head on/off throughout the cruise, and crocodiles.
Side note: We were recommended by 2 friends who went on the river cruise to try the Boma Dinner & Drum show, said to be fun even though touristy.