The son of noted engineer Sir Marc Brunel, Isambard K. Brunel first rose to prominence as the resident engineer of the Thames Tunnel, his father's greatest achievement. The first major river tunnel ever built, Isambard spent nearly two years trying to drive the horizontal shaft from one side to the other. Two severe incidents of flooding injured the younger Brunel and ended work on the tunnel for several years, though it was eventually completed.
In the mean time, Brunel moved on. In 1833 he was appointed engineer of the Great Western Railway, one of the wonders of Victorian-age Britain. Running from London to Bristol (and a few years later, to Exeter), the Great Western contained a series of impressive achievements -- viaducts, stations, and tunnels -- that ignited the imagination of the technically minded Britons of the age. Brunel soon became one of the most famous men in Britain on the back of this interest.
Even before the Great Western Railway was opened, he was moving on to his next project -- transatlantic shipping. He used his prestige to convince his railway company employers to build the Great Western, at the time by far the largest steamship in the world. It first sailed in 1837. The Great Britain followed in 1843, and was the first iron-hulled, propellor-driven ship to cross the Atlantic Ocean.
Building on these successes, Brunel turned to a third ship in 1852, even larger than both of its predecessors. The Great Eastern was cutting edge technology for its time -- it was the largest ship ever built until the Lusitania launched in 1906 -- and it soon ran over budget and over schedule in the face of a series of difficult technical problems. The ship is widely perceived as a white elephant; indeed, there are considerable parallels with Howard Hughes' 20th century Spruce Goose. Though a failure at its original purpose of passenger travel, it eventually found a role as a oceanic telegraph cable-layer.
Brunel suffered a stroke just before the Great Eastern made its first voyage to New York, from which he never entirely recovered. He died ten days later.