Mauna Kea means "white mountain" in Hawaiian and is the home to several observatories including four shown in this photo (from left to right) the Subaru, Keck 1, Keck 2 and the NASA Infrared Telescope Facility. They are operated by a combination of universities, governments, government agencies and the Smithsonian Institute. Universities include U. of Hawaii (no surprise there), CalTech and the University of California. Foreign interests include the UK, Japan, Australia, Canada, Argentina, Brazil and Chile, along with the U.S.
There are a number of companies that will take you on a Mauna Kea summit and stargazing adventure. Because the top is over 14,000 feet above sea level and any clouds are below the summit, there is always a nice sunset from up there. After the sun sets they take you down to about 9,000 feet and set up their own heavy duty telescopes for some pretty spectacular star gazing. They also supply you with cold weather jackets because even in Hawaii it is very cold up there.
One note of interest: Street lights and parking lot lights at major shopping centers and stores such as Wal-Mart all over the Big Island are a dim yellow in color rather than a bright white we are normally used to in the U.S. Although the folks working in the observatories will tell you regular lighting would not interfere with their studies at all, developers and local government try to keep excess light to a minimum, a courteous gesture appreciated but not really necessary since the observatories are located nearly 3 miles above sea level.