Water, Sewage & Effluent September October 2018 | Page 15

Water Sewage & Effluent September/October 2018 13 technology S ilfra in Iceland is considered the clearest body of water in the world. Originating from a glacier and flowing between two tectonic plates, Silfra lets you be in two places at the same time: North America and Europe, with water so pristine that visibility can reach 100m, with depths of up to 63m and temperatures of 2°C. Located in a section of the Earth’s crust known as the Mid-Atlantic Ridge, the 15  000km canyon separates the Eurasian and North American tectonic plates. While most of it is underground, except for at the islands of the Azores and in Iceland, this geological border, accessible only underwater, is reached via the second-biggest lake in Iceland, the Þingvallavatn, in Þingvellir National Park, 60km from Reykjavik. This park is the only place in the country that has been declared a UNESCO World Heritage Site. Every particle of H 2 O that reaches this place has undergone a journey that took 30–100 years, from the nearest glacier, Langjökull. Just 50km north of Þingvellir, is the second-biggest glacier in Iceland. As it thawed, it used to feed the lake, via a river. But, several thousand years ago, Skjaldbreiður volcano erupted and the river was buried. When the ice melts, it continues to flow along the same bed, which is now covered with highly porous volcanic rock. During its journey, the water is filtered and cleaned. Combined with the icy temperature, it becomes the clearest water on the planet. Source: www.dive.is/dive-sites/silfra