The wooded park of the Promenade Museum is criss-crossed by streams and waterfalls from the Saint-Benoît natural water-spring. This natural water-spring flows continuously in summer and winter. It releases an average of thirteen litres of water per second, i.e. over 400 million litres of water per year. Its temperature, which fluctuates between 11°C and 13°C, provides a much appreciated coolness in summer. The quality of the spring's natural water combined with regular Health & Safety monitoring enables it to supply drinking water to the Promenade Museum.
The spring's water supplies an area covering serveral square kilometres to the northwest of the Promenade Museum's estate. The water emerges through a crack, deep from the earth.