The stone of Saint-Samson is a Neolithic stele of 70 tons and 10 m of probable length. Its intriguing leaning position and its very regular morphology have aroused curiosity since medieval times. Three of its four faces—oriented towards the cardinal points—display engravings that were discovered in the 1970s. Now, a new recording protocol has combined 2D techniques for emphasizing the contrast of the engravings (oblique rotating lights) and 3D methods for restoring the volumes of the support (photogrammetry, structured-light scanner). The results obtained have made it possible to implement the first structural analysis of the stone. The north and west faces show an opposition between domestic (cattle, goats) and wild animals (suidae, cervidae, birds, cetaceans), depicted confronted and with their horns or tusks clearly visible. The south face was reserved for the human figure and for iconic artefacts (polished axe, throwing stick, ring disk, steering oar). The four faces have in common the presence of boats. The relationship linking the monument to waterways and the sea is approached by analysing both local legends and the phenomenon of the tidal wave.