Underwater cultural heritage is an integral part of the human heritage and, as such, attention must be paid to its preservation. If the safety of the assets on land is not guaranteed, for the submerged ones the critical issues are greatly increased. Therefore, it is necessary to collect and analyze data that will enable us to enhance and safeguard these assets in the best possible way. The Archimedes project aims to map, analyze and enhance these assets, in different environments. In this paper some techniques for underwater data collection and analysis using a photogrammetric approach will be shown. Particular attention has been paid to the camera calibration phase, a fundamental part of underwater surveys.