The North Sumatra-Mergui Basin is a convergent basin which extends across the Malacca Strait and its coastal fringes in Sumatra, Peninsular Malaysia and Thailand. This report considers just the Indonesian territory. The onshore and shelf sectors are well-explored, with more than 500 exploration wells across over 130 years. Most recent discoveries have been rare and small, but the Benggala discovery (2012) proves material gas potential remains. Notable explorers, including Eni, Repsol, Premier Oil, operate acreage in the more frontier deepwater area, located north of the basin. The large part of the basin’s prospective resources will likely come from this sector, where Repsol and Premier Oil are planning to drill in 2019-2020. The results of these wells will probably determine the level of activity in this frontier play.