Pego De Inferno (Lagoon/Waterfall)

Pego do Inferno, whose name translates as Hell's Pool, is a small waterfall and a deep green pool in the hills a few kilometres inland from Tavira in the eastern Algarve. It is one of those places that locals have long used for a summer swim and that visitors tend to find only by word of mouth. The contrast with the coast is striking: instead of open sand and surf you get shade, pines, running water and the sound of a stream.

The water comes from the Ribeira da Asseca, a modest stream that cascades over a rock lip and into a natural basin. What makes the site unusual is the calcareous tufa, a porous limestone that precipitates from lime-rich water and builds up around mosses and plants over time. Over the centuries this process has given the falls their stepped, sculpted look, with curtains of rock hanging over the pool. The water level and the flow vary with the season, and after a dry summer the falls can shrink to a trickle, while in winter and spring they are at their fullest and the pool is at its most vivid.

Getting there is easy but needs a little care. The road from Tavira leads to a small parking area, with a second one a few minutes' walk further on, and from there a path of around ten minutes runs through pine woodland to the pool. The route is mostly gentle, though the final stretch can be rough underfoot, so trainers or sandals with grip are better than flip-flops. There are no cafes or facilities at the pool itself, so bring water, a towel and a bag for your rubbish. Visiting early in the day or on a weekday avoids the crowds that arrive in July and August, when the pool fills with swimmers and the quiet atmosphere is hard to find.

Swimming is the main draw, and the water stays cool even in the hottest weeks, but take care on wet rock, which can be slippery. Entry is free, and the site is dog-friendly, which is unusual compared with the beaches on the coast. Photographers do best in the soft light of the morning or late afternoon, when the greens of the vegetation and the pool are richest.

The pool is a good half-day trip combined with a visit to Tavira's old town with its Roman bridge, or with the quiet beaches of Ilha de Tavira. Because the place is fragile, it helps to stay on the path and avoid climbing on the tufa itself. Spring is perhaps the best season, when wildflowers line the trail and the falls are strong.