A POOL of crystal clear water which is turquoise in colour as it gets deeper enchants visitors when they arrive at the site in Pulau Betong, Penang.
The chilly water from the hills emerges in a spring and collects in the 2m-deep pool under a shady copse of trees.
Villager Amir Yusoff, 61, who lives next to the pool, said someone built it six years ago.
“The plan was to only make a small freshwater pool for us to take a dip.
“We never thought the water would turn turquoise,” he said, adding that sometimes, he would just sit by the side of the pool and behold the colour to relax.
Amir, who is now the self- appointed caretaker of the turquoise pool, said it had never dried up, not even when Penang suffered bad droughts.
He said that in recent years, word of the pool’s existence got out and visitors from near and far went to see it.
“Tourists came for picnics and to admire the pool’s water which they can drink. They also dive underneath to look at fishes.
“A team from Universiti Sains Malaysia (USM) once tested the water and confirmed that it was safe for consumption,” said Amir.
With visitors gradually increasing, Amir urged them to uphold Covid-19 precautions on top of helping to keep the place clean.
“We are willing to share the pool with anyone but please look after it,” he said.
USM aquatic ecologist Professor Dr Wan Maznah Wan Omar explained that the water may seem blue because in the visible light spectrum, blue light scatters more than red.“Absorption and scattering affects the colour of the emergent light.
“Water molecules absorb longer wavelengths such as red light at 600 to 700 nanometres (nm) while shorter blue wavelengths of below 500nm pass deeper into the water column.
“Bue light scatters more than red light to the surface of the water so what is visible is blue.
“Pure water scatters light in the blue range.
“Water with suspended small particles such as calcium carbonate scatters light in the blue-green range while water with dissolved tannin scatters light in the yellow-brown range,” she said.
Citing an example, Prof Wan Maznah said in highly productive lakes where algae blooms grow, the algae’s pigments absorb blue and red light and scatter the green, making the water look green.
In the case of the pond in Pulau Betong, Prof Wan Maznah said it was worth noting that the turquoise colour occurs only at the deeper end of the pool.
“The spring feeding the pool brings particles of suspended solids which may contain calcium carbonate or colloidal aluminosilicate particles.
“They also precipitate as white sediment which enhances the remarkably bright sky-blue colour.
“Instead of turning the water grey or cloudy, these particles scatter sunlight in the blue-green range, so the water appears turquoise,” she said.