At the very northern end of the Ses Illetes peninsula, the island narrows to a thin tongue of sand and rock that points toward the uninhabited islet of s'Espalmador. This is Pas des Trucadors — and it is covered in cairns. Over many years, visitors have stacked flat stones into towers, dozens and then hundreds of them, ranging from modest piles to elaborate constructions half a metre tall. It is the kind of spontaneous collective act that travel sometimes produces: nobody organised it, nobody runs it, and the result is quietly extraordinary.
At low tide, the channel between Formentera and s'Espalmador is only a few metres wide and shallow enough to wade. Some people do, stripping off their shoes to cross to the uninhabited island and back. The whole area sits within the Ses Salines Natural Park, which means no development, minimal facilities, and an atmosphere of genuine wildness at the edge of some of the most-photographed beaches in Spain. Walk here from the Ses Illetes beach car park — the path north along the spit takes around 20 minutes.