There are Manatee in the Rainbow River and you must go thru the waters at a low speed when using a motor boat.
We came across this sign when leaving the Withlacoochee waters for the Rainbow River. Didn't see any, but they're there!
Here's a website with some beautiful pictures of Manatees ... just incase you've never seen one either! http://www.canyonoutdoors.com/homosassa2.htm
By law, disposable containers and alcoholic beverages are not allowed on the Rainbow River and are subject to heavy fines! All food and drink should be in NON-disposable containers! (such as Tupperware, thermos, gladware, plastic drinking cups, etc.)
Just a warning ...