There's something unusual floating in the waters off Manhattan. Thirty-five years after it was first thought of -- artist Robert Smithson's ``Floating Island'' is a barge covered with soil, trees, shrubs and rocks, led by a tugboat. It will along the Hudson and East rivers beginning today. Smithson was one of the most significant artists of the 1960s, who was very interested in exploring nature and landscapes, and how they were constructed. He came up with ``Floating Island'' in 1970 and unsuccessfully tried to bring it to life. He died in 1973 at age 35 after a plane crash. For...