Inland waterways, such as rivers and lakes have been foci of human settlement and use for millennia. However, underwater archaeological prospection or survey in these environments is often hindered by poor or no‐visibility conditions. While this can be overcome using a range of well‐established geophysical techniques, their application in inland waterways seems comparatively less common than in offshore environments. Possible reasons include the logistical challenges of surveying shallow confined, often inaccessible and uncharted waters coupled with a wider lack of awareness of the submerged archaeological potential of inland waterways. This paper demonstrates one method by which the logistical challenge can be circumvented, specifically the use of low‐cost acoustic systems which combine a single‐beam echo sounder and sidescan sonar. These systems have appeared within the last decade and are smaller and cheaper than their survey‐grade counterparts. Although developed for the sport fishing community, as shown here, they can also be used for archaeological purposes. Their effectiveness for archaeological prospection is illustrated via three case studies from lacustrine and riverine settings in Northern Ireland and by reference to object detection and bathymetric mapping. The data presented indicate that the low‐cost systems are capable of collecting data that is sufficient for archaeological purposes but they are best suited to shallow confined waters where their disadvantages (limited range and depth of operation, reduced image quality) are minimized. Copyright © 2016 John Wiley & Sons, Ltd.

Conservation of historic shipwrecks is prohibitively expensive and in situ preservation and recording is the preferred archaeological approach. Non-destructive high-definition 3D imaging is therefore essential for recording and managing submerged historic shipwrecks. Multibeam echosounders (MBES), the standard tool for hydrographic survey, can produce point clouds to image complex 3D structures. However, wreck imaging is often done using MBES in traditional survey mode optimised for morphological characterisation of the seafloor. This does not necessarily provide high-definition imagery required by archaeologists. This study demonstrates key factors influencing high-definition MBES imaging of wrecks through a controlled field experiment. Results show that optimal highdefinition 3D imaging is achieved through maximising the pulse rate, narrowing the angular sector, using the highest frequency and shortest pulse lengths, applied to at least 3 to 5 overlapping centreline-parallel and offset passes with additional perpendicular/oblique lines. Variations in survey design are demonstrated to exert strong controls on sounding density and distribution, with highdensity on horizontal and vertical wreck surfaces enabled by a combination of overlapping passes and offset lines. Adoption of this method would result in more widespread high-definition 3D imaging of wrecks to benefit archaeological research and develop effective mitigation strategies to minimise loss of the fragile underwater resource.

This paper will present research on the vulnerability mapping of coastal archaeological sites currently being undertaken in Northern Ireland. The ultimate aim of this research is improve current predictions of where archaeological sites and landscapes will be at risk in the future from coastal erosion. The initial stage of this approach uses a suite of oblique aerial photographs to construct a baseline of eroding locations and coastal geomorphology. The erosion baseline can then be integrated with existing historic environment records to obtain a coarse first-pass archaeological vulnerability assessment. Subsequent stages can then use this assessment to prioritize future mitigation such as field surveys or monitoring exercises, or conduct further refinements of vulnerability classifications by incorporating information on site type and positioning on a local scale.

A high-resolution aerial lidar survey (up to 40 points m -2 ) has been carried out in the environs of Knockdhu Promontory in the Antrim Uplands, which is recognized as one of Northern Ireland's most important relict multiperiod archaeological landscapes. This lidar survey was amongst the first such surveys commissioned specifically for archaeological purposes in Northern Ireland and has helped to re-evaluate the archaeological landscape character of a 9 km 2 study area and inform future conservation studies. Sampled ground observation was undertaken in an attempt to provide a higher degree of interpretive integrity. These field observation exercises also highlighted the importance of the high vertical resolution of the data (0.05 m at 2σ (95% confidence level)) in delineating extremely subtle upstanding earthwork features that had hitherto gone unnoticed. Much of the archaeological evidence identified can be broadly ascribed to the early post-medieval period (AD 1599-1750); this includes field boundaries, cultivation furrows, enclosures, transhumance huts, abandoned settlements and associated pathways, but the higher ground of the Antrim Plateau in this locality is also characterized by evidence of prehistoric activities and substantial earthworks survive such as the 'Linford Barrows' and 'Knockdhu Promontory Fort'. The lidar study has identified as many as 285 previously unrecorded potential archaeological sites and amended existing records within the Northern Ireland Sites and Monuments Record (NISMR) and has proved transformational as a technique to 'open up' the Ulster uplands for archaeological study.

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