we paid to complete a full lake cruise with a commentary by a park ranger. I think they only do this once a week and it cost £18 per adult.
Ranger Steve was fabulous. He was funny, well informed and interesting.
We got on at Bowness, travelled to Ambleside, then back to Bowness, and then to lakeside and back. For the full commentary you have to stay on the boat and it takes about 3 hours - it was excellent and would recommend it as a wonderful way to while away an afternoon.
If you can't to the ranger trip then I would still recommend it as a way to get around the lake.More