Last updated: May 25, 2020 at 2:55 am
80 m (262 ft) or the approximate visibility of distilled water. A few locations are claimed to equal the visibility of distilled water, including the Silfra Fissure in Iceland, the Weddell Sea (Antarctica), New Zealand’s Blue Lake (a.k.a. Rotomairewhenua), and some Mexican cenotes. Claims of visibility surpassing 80 metres anywhere are likely overstated. However, the Weddell Sea has the added distinction of being composed of seawater that is teeming with life, including plankton.