More than 1,300 plant species crowd this rugged terrain, mingling Mediterranean, Atlantic, and alpine elements in a way few places manage. The protected beech stands keep to the cool, damp ravines that face away from the sun, sharing the shade with yew and holly. Lower down, the slopes turn to black and red pine, holm oak, and the aromatic tangle of garrigue scrub. Where the wind scours the exposed limestone, hardier plants take hold—gorse, bearberry, and species found almost nowhere else, including the sticky-leaved butterwort Pinguicula dertosensis and the rosette-forming saxifrage Saxifraga longifolia. The rock itself shapes what can live here. This is karst country, all fissured limestone and hidden water, and the plants that thrive have learned to read its moods: to find the damp crease, the sheltered ledge, the north face where a relic of the Ice Age can still hold on.

The undisputed lords of Els Ports are its Spanish ibex, whose population of roughly 6,000 is the largest in the country. Watch a ridge at dawn and you may catch them picking impossibly casual lines across near-vertical rock. They share the massif with otters in the rivers and with wildcats, foxes, wild boar, and badgers in the forests. More than half of all the reptile and amphibian species in Catalonia turn up here, from pond turtles to marbled newts. Overhead, the drama belongs to the birds: vultures riding the thermals off the cliffs, golden and Bonelli's eagles, peregrine falcons folding into dives, and Eurasian eagle-owls hunting the dusk. Orioles flash gold through the canopy, and blue rock thrushes sing from the crags. In the rivers below, crayfish and native fish hold on while clouds of dragonflies and butterflies work the water's edge—a whole living system stacked from streambed to summit.

People have moved through this massif for thousands of years, and they left their marks: prehistoric cave paintings, scattered stone structures, the layered traces of Iberians, then Arabs, then Christians, each adding settlements and customs to the folds of the mountains. For centuries the forests were worked hard—timber for shipbuilding, land cleared for farming—and small communities scratched a living from the stone. Then, in the middle of the twentieth century, they left. Rural depopulation emptied the high villages, and as the people withdrew, the wildness crept back in. Trees reclaimed the terraces; goats reclaimed the crags. Alarmed at what might be lost, the Catalan government moved to protect the massif's biodiversity and its dramatic geology, and in 2001 Els Ports was formally designated a natural park. The abandonment that hollowed out the villages is, in a strange way, what made the park possible.

Two long-distance paths thread the park. The GR-7, part of a route running all the way from Andorra to Tarifa, crosses the massif lengthwise through mountain refuges and the village of Paüls; the GR-8 branches off toward Beseit in Aragón. Cyclists can follow the Via Verde Val de Zafran, an old railway line turned greenway that runs from Tortosa to Horta de Sant Joan—bring a light, because the tunnels are long and genuinely dark. On a hot day, the reward is a plunge into one of the park's designated pools, El Toll Blau or El Toll del Vidre, where cold mountain water gathers in basins of polished stone. From the high viewpoints near Mont Caro, the whole of the Terres de l'Ebre unrolls below: the Ebro winding toward the sea, and the crags falling away in every direction. On the western edge, the wild does not stop at the boundary—it carries on into the neighbouring Tinença de Benifassà park in Castellón.