The lounge was a posh nightclub that often did very good business and provided Penguin with a perfect cover for his illegal activities. As the name suggests, it had an arctic theme with an artificial lake in the middle of the main room with an iceberg and real seals in it. Many of Gotham's criminals could be seen there including Joker and Rupert Thorne. Penguin also had a back entrance which he used for his illegal meetings.
The Penguin's regular staff for the Iceberg Lounge were several attractive women in bowler hats who doubled as his criminal henchmen. Though the Penguin usually avoided direct criminal activity once he began acting as a "Legitimate Businessman", he still found it necessary to use them as bodyguards or assassins.
The Iceberg Lounge had an appearance originally written in Paul Dini's screenplay for Batman Beyond: Return of the Joker, in which the Lounge was to appear when Batman and Batgirl infiltrated it during the flashback sequence, knocking unconscious the guards and interrogating the Penguin in order to discover something about Robin's and the Joker's whereabouts. The scene was cut from the finished version of the film, but remains in the film's comic book adaptation along other deleted scenes.