I wasn't sure we would see any and had prepared Ellison for this disappointment, but she was adamant that there would at least be a few. And there were. Six of them swimming right at the entrance to the springs run - four adults and two babies. The kayakers and paddle boarders were lucky enough to watch them from a relatively close vantage point, but we could still see them clearly from our spot on the dock lookout. They are so slow, friendly and curious - making it easy to forget that touching (and interaction of any kind, really) is prohibited. We watched them for about ten minutes until they swam off away from the springs and up the Suwanee River. Ellison was super excited, the brush with manatees making the day a success regardless of whether or not we did any hiking.
Just FYI, if you are looking for places to view manatees throughout Florida other than Manatee Springs, this article is really helpful.
In addition to the boardwalk, there are some longer trails at Manatee Springs and we covered about half of them on this hike - total mileage combined is around 8.5 miles and we did about 4.5 this visit. The paths are wide and well maintained, making for a very easy walk. And except for a pair of four wheelers, we didn't see a single person the entire time we were on the trails. The springs were relatively crowded, but apparently not one of them wanted to explore the park on foot. It really is their loss because this area is so beautiful.