Design work for a floating bridge across the Derwent River began in 1936. It was opened for traffic in 1943 and operated until 1964 when it was replaced by the current Tasman Bridge.
Section of the old floating bridge were towed away and used for various other purposes. The only two sections still surviving were used to make a jetty and breakwater at Alonnah. For pictures of the bridge in its prime, see this Tasmanian Times article. For an interesting look at Hobartís various bridges over the years, see this video.