Sultaniye is a neighbourhood of the municipality and district of Köyceğiz, Muğla Province, Turkey.

[4][5] The Sultaniye hot springs are located on a fault line at the southwest bank of the lake, on the slope of Ölemez Mountain.

Sulfurous water of 40°C seeps out of a crack next to the spa’s domed thermal bath, spreading the nasty smell of rotten eggs over the complex.

The mildly radioactive water is rich in Radon content and furthermore contains sulfur, iron, calcium, potassium, and other minerals.

It is recommended for -amongst others- skin complaints, arthritis, muscle fatigue and rheumatism.