Pedra do Mariano ("Mariano's stone) is a large rock wall full of indentations and overhangs at a depth of approximately 14 meters off the coast of Portimao. The wall has two terraces leading to a mixed bottom at around 16m in depth of small rocks and loose pebbles, which is inhabited by gorgonians of different colours and sizes.
Marine life is abundant in the overhangs, which deserve careful and attentive exploration. On the bottom, it is common to find scorpion fish and goby, as well as larger fish, like white seabream, zebra seabream, gilthead bream and seabream. Given the relatively easy orientation and the existence of lots of boat traffic in the zone, divers are advised to ascend using a cable or line, launched using a surface marker buoy.