to descend it and climb up towards Ololbizzi, a charcoal burners' circle in the upper part of the Bacu. Day Four The last day starts from Bacu Su Feliau and ends 7 km later in Cala Sisine (40°10'45"N 9°38'1"E). It offers a large variety of scenery, the highest altitude reached during this stage is 480 m. The estimated travel time is 6.5 hours and the technical difficulty is ranked IV on the UIAA scale. This makes this stage the second most difficult of the Selvaggio Blu. At the start of this stage, it is necessary to climb a juniper trunk with giant moss-covered oaks. The route then traverses a gully and is then marked with blue waymarks painted on rocks. These mark the way to exit the woods, utilizing ancient mule tracks, and gives a panoramic view of the sea. Before descending, there is the possibility to climb a cliff named "rottura delle altezze" (which means "breaking the heights") from which walkers can look at the sea 200 m below. One of the paths leads to the ovule Piddi, meaning Mandragora or Mandrake in Sards; this poisonous plant grows all over the Supramonte. Helped by the locals, Verin and Cicalò built a network of mule tracks that, with a series of bends, pass through the most impervious gullies and lead to the sea, which can be seen only in Cala Sisine; here there are docks built to transport charcoal and woods. From Cala Sisine it is possible to return to the starting point by the sea with an inflatable boat or by land with a SUV. Variations of Selvaggio Blu There are several different versions of the Selvaggio Blu: The first is the original one conceived in 1987 by Mario Verin and Peppino Cicalò that goes from Pedra Longa to Cala Sisine. The second one is called Selvaggio Blu+Blu (Wild Blue+Blue) conceived by the Alpine Guide Marcello Cominetti together with Explorando Supramonte in 2014. It lasts 7 days and has different variations compared to the original trek: there is a stop at Grotta del Fico and at the beaches of Cala Mariolu and Cala Biriala and a passage through Cala Goloritzè. The third one is called Blu Selvaggio (Blue Wild) and is considered the hardest one. It goes from North to South, in the opposite direction of the original trek, and includes passages not covered in the original one like