Crystal River, FL
Well worth it if you are in the area. We took a private boat (six people) and it was $45 ea. for a 3 1/2 hour trip, roughly 90 minures of swmming in the river. We saw 5 in total, but at this time of year they have almost all gone out to sea. The two we saw most were a 13' Momma that slept the whole time, and her 6' baby that was very playful - swam in to me twice, flipping me over both times.
The water was not that clear due to a storm that went by the day before. The pic is a screan cap from my GoPro.