Ground penetrating radar (GPR) is a commonly-used geophysical technique, yet the use of water-penetrating radar (WPR) has been less-well researched and published on. This is surprising, given the wide use of GPR on ice and the success of early aquatic experiments in the 1970s and 1980s. The past 15 years have seen advances in modes of antenna deployment, understanding of limiting environmental conditions and applications to geotechnical engineering (e.g. bridge support scour), siltation (e.g. sedimentation in reservoirs and flood-relief water-courses, sometimes due to climate change); location of sediment cores for palaeoecology; search and rescue operations and environmental crime (e.g. illegal dumping of waste in water). This manuscript will review the above, from common techniques through to typical applications with geotechnical engineering, archaeological and forensic case studies that demonstrate some of the applications covered in the review.