In order to gain accurate information on coral growth increments, the buoyant weight technique (BWT) is a commonly employed technique. However, this method is not readily applicable for in situ studies, as individual coral fragments need to be retrieved regularly to be measured in the lab. The use of 3D photogrammetry on the basis of underwater photography eliminates both of these issues. The pictures as a source for the data can be directly taken from the in situ setup with underwater photography. Consequentially, no transfer of specimen to the lab is required, stress is limited for the coral specimen. This new digital tool further enables data acquisition in remote places without laboratory access. The process turning underwater pictures into 3D models involves three steps, including the creation of a 3D model, and the subsequent calculation of its respective volume. Potential pitfalls of this application are discussed. This non-invasive method is beneficial not only for coral reef research but also applicable for projects with other sessile animals.