Take your canoe or kayak, or rent one and go have fun on the Calusa Blueway Paddling trail and explore the small channels around the island. So much wonderful nature here to see and photo! You can put you kayak or canoe in near the 1st parking lot.
Lovers Key has plenty of places for you to take the kids and go fishing. You may want to check for signs about no fishing, because some areas have alligators and you wouldn't want to hook one of those, if you do, quick cut the line!!
Lovers Key has a really nice bike trail, so bring your bikes and take a ride. Make sure you bring water too, it gets hot! Plenty of wild life for photos and great views. Lovers Key is rather flat, so it will not wear you out, and there are plenty of trees to duck under if you need some shade.