I took a boat tour around the lower part of the lake. It was interesting, but not something I would spend money on again. It's a big lake and the water is sparkling clear. You can rent boats at the marina.
The funniest thing we saw in the marina as we were waiting to board was a couple and a young girl who had rented a rowboat. I did not have the nerve to take their photo, but they apparently had never rowed a boat before, as they were rowing backwards. In other words, instead of the pointed end of the boat headed forward, the stern was in the front. They were seated right, just pushing on the oars instead of pulling!