Antarctica was a center piece of the Gondwana supercontinent. About 85 percent of Antarcticas 10000 km long continental margins are of a rifted divergent type, and about 1200 km have been converted from a subduction-type to a passive margin after ridge-trench collision along the Pacific side of the Antarctic Peninsula. The separation of South America, Africa, India, Australia and New Zealand from Antarctica and the creation of a continuous Southern Ocean began in the Jurassic and continued until the mid Tertiary. In recent years, the amount of geophysical data along the continental margin of Antarctica has increased substantially, which allows to differentiate the crustal characteristics of its continent-ocean boundaries and transitional zones (COB/COT). The data and geodynamic modelling indicate that the cause, style and process of breakup and separation were quite different along the Antarctic margin. A circum-Antarctic map will show the crustal styles or the margin and the location and geophysical characteristics of the COT. Definitions of the COT and and understanding its process of formation has consequences for plate-kinematic reconstructions and geodynamic syntheses.