The ongoing conversion and degradation of insular Southeast Asian peat swamp forests causes globally important carbon emissions and leads to loss of unique biodiversity. Little quantitative information is available on the dynamics of peat swamp forest conversion. In this case study, we present a time-series of peatland conversion and degradation in the Air Hitam Laut peatlands in Jambi Province (Sumatra, Indonesia), which included the Berbak National Park. High-resolution (10–60 m) satellite imagery was used to map land cover and degradation status for nine time slices between the 1970s and 2009. Nearly-pristine forest cover was shown to have declined in the study area from 90 to 43 per cent, inside the Berbak National Park from 95 to 73 per cent and outside the National Park from 86 to 25 per cent. Outside the protected area, 66 per cent of former nearly-pristine forests turned into degraded forests or unmanaged deforested areas. Large-scale oil palm plantations accounted for 21 per cent of the formerly nearly-pristine areas and small-holder agriculture for 8 per cent. The conversion to plantation has fast accelerated since 2002. Conversion from nearly-pristine forest to plantation typically took around 6 years, at times up to 10 years. Better understanding of conversion and degradation dynamics will allow for improved estimates of the implications of management planning decisions taken in peatland areas. Copyright © 2011 John Wiley & Sons, Ltd.