Some of the nightclub's more secret areas include the Penguin's office and armory, and some of the Iceberg Lounge's hidden back rooms, which serve various criminal purposes. Batman often infiltrates the Iceberg Lounge to keep an eye on The Penguin's after-hours activities, usually under the guise of Matches Malone. The Iceberg Lounge has been frequented by many major and minor rogues alike, from the Joker to Amygdala.