We hang out on the downstream side of 521all the time, one of my of favorites in the pool, Many nights you will find me on the hook their just inside the slough.Good spot, another one of my favorite is if you can wiggle deep into two branch, thats nice two.
521 is the Island across from the Duck Club, Two Branch is just above Kinders - a shallow water area for anchoring on the IL side of the island. (Of course it may be awhile before it's shallow)
Two branch is very nice. The waters 3-4 feet deep in the pool at the beginning near Kinders.Nice place to hang out in the water. All sand on the bottom. On the Illinois side there is a beach with some condos behind it. The top of Hat is also nice , but the exposed sand is private property and I hear there have been tickets handed out by Ill. Conservation agents. Just keep your boat and your feet in the water , and supposedly your legal.