An absolutely perfect way to spend a half day!
Drive over to High Springs, FL and launch from The Canoe Outpost: https://santaferiver.com/
They offer canoe, kayak and paddle board rentals (as well as life jackets).
You can either paddle downriver and set up for a shuttle pick-up with Canoe Outpost, or you can paddle upriver to where the Santa Fe River comes back up from being underground at the edge of O'Leno State Park.
I prefer to travel upriver and back (a roundtrip of 6 miles) because after you pass 4 houses, there are no more houses and only the sound of the wind and birds for miles. I have made this journey 3 times now, and definitely will continue going as often as I can.
One note before going upriver-- if there have been heavy rains a few days prior to your trip, you may want to go downriver and catch the shuttle. The current gets pretty strong after a heavy rain, so going upriver is extremely challenging under those circumstances. If no rain, then go for it, as you can easily paddle your way up.