The Swahilian Coastal Forests in eastern Africa are recognised to be a globally important habitat containing large numbers of endemic species, yet are still poorly known over much of their extent. Floristic diversity and endemism in these forests appears to peak in SE Tanzania, where only a few forests have hitherto been surveyed. We carried out a digital analysis of Landsat Thematic Mapper (TM) data to identify other potential areas of Coastal Forest in Lindi and Kilwa Districts, SE Tanzania, followed by a field survey to ground truth and fine-tune our analysis. Our analysis has identified, mapped and sub-classified all remaining areas of Coastal Forest in Lindi and Kilwa Districts, and includes the discovery of a large and hitherto undescribed area of Coastal Forest at Namatimbili, which would make it one of the largest known blocks of contiguous Coastal Forest in eastern Africa. This forest furthermore appears to be minimally impacted by human disturbance. Given the rapidly increasing threats to forested vegetation in this area, urgent efforts are required by the conservation community to ensure the immediate and continued protection of Namatimbili forest.