Capsule: Key Biscayne is the largest of the Miami area islands (not counting Miami Beach, which doesn't seem like an island), and it is also the southernmost, set between Biscayne Bay and the open Atlantic. Older homes on the water with spectacular vistas are being replaced by large new homes, and luxury condos abound. Key Biscayne is more of a self-contained community -- with more shops and restaurants -- than most Miami area islands.