Since the beginning of time, humans have wondered what lies beneath the ocean. As technology has moved on we have been able to go deeper or stay down longer, but the time available at depth on deep water archaeological sites is limited by Physics and Physiology. Our ability to document what lies on these deep sites has been limited to a few photographs, or some video, but it has not been realistically possible to properly research and document these sites. With the advent of digital photogrammetry it is now possible for us to scan a wreck site and bring back high resolution digital 3D models that are accurately scaled and can be used to show exactly what lies beneath. John Kendall is a GUE Tech and Cave instructor and for several years has been involved with GUE's projects across the world. He will be presenting some of the findings of these projects as well as talking about how Photogrammetry works, and how it can be useful for divers.