When I'm on an adventure, I never ask other people for directions. This is not out of stubbornness or irrational male pride, but something I learned from experience. Other people are used to getting around in cars and boats, and simply have no idea how far something is by foot or by kayak.
Invariably when I ask someone how far away a place is, they give an estimate in time, not distance. "It's only five minutes up the road." Well, they mean five minutes by car, not on foot. 55mph equals 80 feet per second. I don't walk that fast, and I doubt you do either. So five minutes by car is 24,000 feet, or 4.5 miles—that's over an hour of walking.
The same applies when out on the water. Average kayaking speed is the same as average walking speed, and boaters just don't know the distances between things. So ignore estimates of distance and time from boaters.
I have not encountered the term "tree island" anywhere other than Florida, and so it is worth explaining here because it can cause confusion. (The term applies to the geography of coastal Georgia and South Carolina and may be used there too, I'm just not aware of it.)
A tree island is a small rise within a marsh that is just high enough above the surrounding landscape that it does not become inundated with each high tide. Trees colonize the spot, and build the mound further. The picture above, taken by me near the Chassahowitzka NWR, is a typical tree island.
On maps of Florida and the Gulf Coast in particular, one finds numerous locations that have been named and identified as "islands." But most maps do not distinguish between tree islands, which are surrounded by marsh and are inaccessible by kayak or boat, and typical islands surrounded by open water.
While planning a trip, or once out on the water, you might study a map and decide to camp at one of these "islands." And while yes, they are technically islands in that the surrounding marshes flood with each high tide and are not solid ground, the marshes are an impenetrable barrier to reaching the island.
This can be frustrating—especially when paddling late in the day, in need of a campsite, and dozens of these islands are tantalizingly close, yet unreachable. Despite this, I take great pleasure in knowing that there are hundreds, possibly thousands of islands around Florida that have never been stepped on by human beings.