The Pearl is a magnificent structure. Formally opened to the public on 21 June 1991, it combines utility and vision. Hollow steel framing supports the glass dome and walls that link six aluminum-sided tanks, each of which can contain 4 million liters of water averaging 85°C (185°F). As part of The Pearl's heating system, hot water is pumped through the metal framework in winter, while cold water flows during summer, thereby producing a comfortable year-round environment. The Viewing Deck on Level 4 takes full advantage of the panorama enjoyed from Oskjuhlid; telescopes mounted at each of the six corners of the deck with recorded descriptions in Icelandic, English, Norwegian, German and French.