Cerro Dragón, Nature reserve in Iquique, Chile.

Santuario de la Naturaleza Cerro Dragón protects a seif-type coastal dune 4 km long and 150 to 550 m wide, rising 220 m above a low rocky marine terrace. The terrace sits 100 m above sea level, giving the area a total height of 320 m beside Iquique. The dune is no longer fed by coastal winds, making it a relict formation.

The dune formed about 20,000 years ago during the last glaciation, when the sea level stood 100 m lower and coastal winds built and fed the sand body. It is now relict: coastal winds no longer supply it with sand. Before protection, building permits were granted on its western slope, and large volumes of sand were removed for construction. On 8 April 2005, Decree Exento No. 419 of the Ministry of Education declared it a Santuario de la Naturaleza.

The dune's name comes from its seif shape, whose crest resembles a dragon's back along the coastal terrace. Since the 2005 declaration as a Santuario de la Naturaleza, the site has been used for guided school and university visits on desert geomorphology and the camanchaca fog that keeps relative humidity near 75%.

The dune lies beside Iquique, reached by road from the city. Its four-kilometre length and 220-metre height above the marine terrace mean little shade, so carry water and sun protection. The camanchaca fog keeps relative humidity around 75 percent, and rain averages only 1.9 mm a year.

The dune is a seif-type coastal formation, a ridge aligned with the prevailing southwesterly winds, four kilometres long and 150 to 550 metres wide. Its sand is no longer replenished by coastal winds, which is what makes it relict. Look for the low rocky marine terrace at its base, about 100 metres above sea level, with the dune rising some 220 metres above it.