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A unique natural wonder awaits visitors
to the western part of Yellowstone National
Park in the US state of Wyoming. Grand
Prismatic Spring is the largest hot spring
in the United States and the third largest
in the world. The basin measures
approximately 75 × 91 metres and is 50
metres deep. The spring discharges an
average of 2,000 litres of 71 °C water per
minute.
Apart from its impressive size, what
makes this spring so special is the range of
colours, which resemble a rainbow. This is
due to the single-cell microorganisms that
Nature’s play of colours
form a biofilm around the edges of the
mineral-rich hot spring. They adapt to the
water temperature and concentric circles in
colours ranging from dark green to orange
and red can be seen in the water depending
on the ratio of chlorophyll to carotenoids
as well as the time of year. The centre of
the spring is free from microorganisms.
The deep blue colour stems from the purity
of the water in the centre of the pool.
177 years after it was first discovered by a
group of trappers, Grand Prismatic Spring
is today one of the top five hot spots in
Yellowstone National Park.