Manatee Springs Scenic Trail is a 3.7 mile moderately trafficked loop trail located near Steinhatchee, Florida that features a lake and is good for all skill levels. The trail offers a number of activity options and is accessible year-round.
This park is amazing, although we visited Easter weekend and it was pretty crowded. Even so, the hiking trails were dead empty. We took the scenic trail all the way up to the northernmost point in the park that emptied out at a boat slip where we ate lunch. Be careful of ticks around here, we picked up five or six of them just sitting by the river. The round trip was about 7 miles I think, and coming back and sticking our feet in the spring was the greatest ending to a hike ever. Definitely bring lots of bug spray though -- if we stopped for even a second, we were literally swarmed with gnats. Really the best solution would probably be a netted hat.
After our hike, we rented a canoe ($20 for 2 hours) and went down the spring out into the river where we saw 3 alligators and a heckton of turtles, it was awesome. Also the barbecue place here makes for some excellent post-hike food :)
You not only have the advantage of hiking, biking, and enjoying nature, but also can dive, swim, snorkel there... really a nice place!