# The Usage of Virtual and Augmented Reality in Underwater Archeology
## 1 Introduction  
Underwater cultural heritage is anmeasurable historical and archaeological resource, with many diverse archaeological sites, such as sunken cities, shipwrecks, prehistoric sunken landscapes, sacrificial sites, and the remains of ancient fishing installations and ports, scattered around the world. Underwater archeology includes the study of sites that come from different periods and are located in various locations, including those not only in seas and oceans, but also in lakes, rivers, and swampy areas [1; 2; 3]. Specialists in the field of underwater archeology indicate that there is much more heritage underwater today than it might seem [4; 5]. However, this heritage is often underestimated and destroyed, both by the activities of nature--strong currents, biodegradation, such as borers' activity, etc., as well as through human activities, for example, deep-water trawling or treasure hunting [4; 6; 7]. Underwater cultural heritage is also usually less accessible to the average citizen than archaeological sites located on land. Access to these sites is difficult due to a number of restrictions imposed by the underwater environment or legal framework [4; 8]. For this reason, the potential of underwater cultural heritage, in particular in relation to maritime and coastal tourism, is only considered to be exploited to a very small degree [9]. Therefore, in the case of this field of science, it is particularly important to develop technologies and tools that will, on the one hand, allow the preservation of sites for future research purposes, while making them available to the widest possible group of specialists, and, on the other hand, they will make it possible to make the results of work available in an attractive way to a wide audience [4; 6]. Virtual and augmented reality (VR and AR) technologiescan help in achieving these tasks and can contribute to increasing the exploitation of underwater archaeological sites, in a way that is both sustainable and accessible to large-scale tourism [9; 10]. Broadly speaking, VR technology can be defined as a fully artificial environment (usually a simulation of physical reality) in which a person can freely look around (and even move) and establish various types of interactions with it or have the ability to interact with it [11; 12; 13]. The definition of this concept is important due to the fact that in the field of archeology, it is very often used to represent almost anything that contains 3D visualisations [14; 15]. In turn, the term AR means an environment in which computer-generated elements are artificially superimposed on the real image [12; 16]. It is worth noting, taking into account the development of current technologies, that specialists in the field distinguish more forms than just VR and AR. In the literature, it is possible to encounter other concepts, such as augmented virtuality (AV) or mixed reality (MR), in which virtual reality is enriched with elements from the real world [17; 18]. However, for the purposes of this article, only two basic concepts will be used--VR and AR--due to the lack of a clear dividing line between AR and MR [18]. The thesis of this work is the statement that VR and AR technologies can provide significant support for underwater archeology activities, both at the research and educational levels, and are a useful tool in popularizing the topic of underwater research. The idea behind the use of these technologies is to offer both archaeologists and the wider public a new perspective on reconstructed archaeological sites, which enables archaeologists to analyze material obtained directly from the reconstructed site--a virtual site, and at the same time allows the wider public to \"immerse\" themselves in a realistic exploration of selected archaeological sites. These technologies are particularly useful in hard-to-reach places, such as the deep sea, where time and skills play a significant role in reaching a given object.