Tibetans stocked with tents, towels, snacks and beer bathed in rivers in the suburbs of Lhasa, Tibet autonomous region, over the last seven days in observance of the annual Bathing Week.

This year's festival fell between Sept 9 and 15, or between the third and ninth days of the eighth month on the Tibetan calendar.

Groups of people gathered beside rivers and streams in the city's suburban valleys for the bathing activities, enjoying picnics and other entertainment activities.

Tsetan Dorje, a Tibetan astrological academician from the region's Institute of Astronomical Calculus affiliated with the Mentse Khang or Hospital of Traditional Tibetan Medicine, said that according to traditional Tibetan medicine theory and astronomical calendar calculations, a special star appears in the sky during the first week of the eighth month on the Tibetan calendar, which is known as Karma Riga.

"At this time, all water sources are endowed with eight qualities — coolness, sweetness, lightness, softness, clearness, purity, when drunk, and soothingness to the stomach and throat. All water is transformed into amrita," Tsetan Dorje said.

"Bathing in water during this period will contribute to one's health, including preventing and treating diseases, eliminating dirt and miasma."

Nyima, a chief physician of the Tibet Institute of Tibetan Medicine and Astrology, said Tibetans call the star Richi or Riga, which is one of the 28 motion stars of the universe.

"During the first week of the Tibetan eighth month, the star is nearest to Earth and its light reflects Earth," Nyima said. "Tibetan people believe all the plants, and especially all the water, are empowered with herbal and medicinal functions at this time, which is why they love to bathe in ice-cold rivers."

Kunga Tsetan, a resident of Lhasa, said he is a fan of the interesting tradition, and goes to the river to bathe a few times every year.

"This year, I have been to the river three times to bathe with my family and friends," he said. "We had the opportunity to gather and have picnics. It's not only a health-supporting activity but also a good opportunity to spend time together."