I took a trout ecology class for grad school and loved the experience. I was the fly fishing geek asking all the questions... some of which stumped the professors!
In one class, we snorkeled a gin clear small trout stream. It was one of the most memorable things I've done. You can literally use your hands to pull yourself upstream to within inches of trout and watch them feed. We rented scuba grade wetsuits to stay warm and help with floatation.
It was very interesting to watch the pecking order between large fish in the small pools. Also interesting to see trout each junk like small bark or sand and spit it back out. They are also sampling, which is what they must do with our flies too!
Montana Angler Guide