The study of natural heritage largely depends on its preservation because global climate change, natural disasters, mass tourism, terrorism and human negligence greatly affect changes in the landscape, and thus protected areas. In recent decades, geospatial technologies have been affected by a process of rapid development. They enabled the documentation of the current situation and the development of high quality models for the purpose of preserving and promoting protected areas. The research area of this graduation thesis was Lake Zmajevo oko near Rogoznica. The objective of the research was to determine the accuracy of the integrated measuring system of combinations of RTK GPS and multi-beam depth sounder, given that it was used for the first time in the Republic of Croatia and to obtain information on the basic characteristics of the lake (area, volume, depth). Also, one of the objectives was to map and classify the bottom of the lake as well as to identify underwater tunnels. Aerial photogrammetry used by the Phantom 4 Pro UAV equipped with a high-resolution camera covered the water surface of the lake and the wider coastal area in the buffer zone of 100 m. The bathymetric survey, for which, for the first time in the Republic of Croatia, an integrated measuring system of combinations of the WASSP S3 multi-beam depth sounder and the Hemisphere V320 GNSS smart antenna was used, covered the bottom of the lake. An integrated measuring system with an operating frequency of 160 kHz has fully enabled the mapping of the bottom and ten side tunnels (cracks). In the final phase of the research, the data collected by both methods were combined and an integrated model of a high quality lake was developed. Based on the 2.5D and 3D models, the volume, area, and length of the lake shoreline were calculated. The accuracy of the model obtained by aerial photogrammetry is < 5 cm. The vertical precision of unfiltered data of the integral measuring system is 6.8 cm, and the horizontal is 11.8 cm. In the Lumion software, a virtual walk through the lake was made for the purpose of promoting. A physical model of the lake, which can serve as a souvenir, was printed by the help of the 3D printer Prusa i3 MK3. The collected high quality data are the basis for future research in this protected area.