At this very moment, hundreds of manatees are jam packed into the warm waters at Blue Spring State Park in Orange City, which means the live stream is arguably the best thing on the internet today.
As of this morning, the park staff counted 363 manatees from the boardwalk and Save the Manatee Club staff counted 418 in the canoe.
Since it's not always a guarantee that you'll get in to the park (they often hit capacity early in the day), the fine people at the Save The Manatee Club have a handy live stream that is definitely worth checking before you make the drive.
If you're having trouble viewing the manatee cam, try it from here. It's also worth noting that in the evening they typically run an edited loop.
Blue Spring State Park is about 30-45 minute drive from Orlando, and charges $6 a car. Get their early.