A large number of clonal isolates of the prymnesiophyte Phaeocystis antarctica have been established at the Alfred Wegener Institute in Bremerhaven, Germany, to address questions on the genetic diversity and ecological response patterns to climate change. However, at present the wider scientific community cannot access these strains and their long-term conservation, (currently by serial transfer), cannot be assured. Cryopreservation could provide the solution to these issues, as it would guarantee the long-term security of this genetically and ecological invaluable collection. This study outlines the successful application of conventional approaches and the use of novel, combined non-penetrating and penetrating cryoprotective strategies that have been successfully applied to the different life-stages of this alga.