On 11 March 2009, Indonesia delivered to the United Nations Secretary General a list of geographic coordinates defining a revised system of archipelagic baselines. This development represents significant progress for Indonesia. Although Indonesia has a long history of championing the archipelagic State concept in the law of the sea, it is the first time that it has designated a complete, closed system of archipelagic baselines. Three changes were made to the previous version of Indonesia’s archipelagic baselines, which were established in 2002. The objective of this commentary is to assess Indonesia’s revised system of archipelagic baselines with a particular focus on the three changes: in the Sulawesi (Celebes) Sea to the east of Borneo, around Timor Island, and in the Indian Ocean off the south coast of Java.