The archipelagic regime, one of the novel aspects of UNCLOS, is a quartum genris , combining characteristics of internal waters, territorial sea and straits used for international navigation. The present article assesses the relevant UNCLOS provisions, by themselves, and in light of the South China Sea and Düzgit Integrity awards. The former clarifies the conditions under which a State may draw archipelagic baselines, the second postulates that, beyond various obligations expressly provided for in the Convention, the archipelagic State must exercise its sovereignty respecting the principle of reasonabless and proportionality. It remains to be seen if these decisions correctly assess the state of the law and if their progressive development dimension will ripen into consensual interpretation of Part IV UNCLOS.