The S.S. Platypus is a cargo ship in Grand Theft Auto IV. Niko served as a crew-member for several months. It was involved in smuggling operations, including diamonds and sports cars. When Niko arrives in Liberty City, the ship is carrying immigrants from across Europe, including Spain and Germany.
According to news reports later in the game, the captain and entire crew of the Platypus disappeared shortly after the ship docked and the passenger disembarked. One was found in the Humboldt River with whip scars on his back (the man who was engaging in S&M with a woman in the first scene). The ship remains docked in Broker throughout the game.