The Essex tidal estuaries are the site of a number of timber-built fish traps, their distribution being particularly dense in the Blackwater estuary where six sites have been identified through the work of local archaeologists and aerial reconnaissance. The Blackwater examples are Saxon in date (Strachan 1998) and comprise large and complex monuments, comprising numerous wooden posts in various alignments, along with wattle-work (sails and rods) and basketry. The recovered information adds to the understanding of these and other fishtraps in the Blackwater estuary and provides measurable data with which to assess the nature and rate of erosion taking place in this inter-tidal environment. Additionally, a number of methodological lessons have been learnt that are of benefit to the improved investigation of such monuments in the inter-tidal zone.