This little island is fun if you're a boater wanting to hang out in the water or look for shells. There is not much to this island as you can see the entire island no matter where you are standing. It is pretty popular so if you aren't into crowds or making new friends, you may want to stay at home or around you boat floating with family & friends or reading a good book.
Nice open area for camping (although there are no specifically cleared sites) so you do need to be mindful that there are lots of plants, shrubs, sticks and stones which can make being in a tent pretty rough if you don't have a good pad and a tarp to protect your tent. You can find some sandy spots tucked into the vegetation every so often along the "beach", but you won't fit a large tent in these areas. Overall, a little difficult to "camp" here and is only accessible via boat, canoe, kayak…bring everything you need to eat and drink and then remember to pack it back out.
Although, you do have easy access to the waterways for exploring and fishing.
Also, you need to get a free camping permit and this is a leave no trace site which means leave nothing…
The other reviewer did a good job of listing out all the points about the facilities and the rules.
Shell Key is one of the larger uninhabited islands off of the west coast of Florida near St. Petersburg. It is managed by the county, and all campers wishing to stay must get a (free) camping permit from Pinellas county. The key itself can only be accessed by water and you must carry in/out everything as there are no bathroom facilities available and all campers must bring a port-a-potty.
Once you decide to stay, you will be amazed by the white sands, abundant wildlife, crazy beautiful sunsets all while pitching your tent among the seagrass in one of the designated camping spots. On the west coast of the island is the blue waters of the Gulf of Mexico, while only footsteps away is the lush waters of the Intercoastal waterway. You can enjoy most water activities as well as what nature has to offer from bird and dolphin watching to fishing and hiking the almost 2 mile long island.