Hot water and plenty of it -- and no one has to heat it. Abundant hot water is supplied by nature in some parts of the world. In Iceland, for example, this free naturally heated water is put to a variety of uses.
Iceland's most recent and controversial effort to use this underground resource is represented by the geothermal power station at Krafla, a few miles east of Lake Myvatn in the north-central part of the country.
The scheme is simple enough in principle: Holes are drilled into the earth to pockets of superheated water. As the water rushes up the pipe it turns to steam. The steam is used to power conventional electric generating turbines.
Unfortunately, this simple idea has been difficult to put into practice. The plant, a significant investment for a country with a population of less than 250 ,000 people, is producing only a fraction of the 70 megawatts for which it was designed.
Setbacks include insufficient steam and corroded pipes, but the most dramatic problem at Krafla is caused by the very nature of the region.
Even minor earthquakes offset bore holes and crack pipes.
In view of the difficulties a visiting British geologist was asked if he didn't think the project was a mistake.
"No," he replied. "You always take a chance when you look for energy, whether its drilling for oil, or whatever. It's a risk, but a reasonable one."
While the Krafla project has become a subject of jokes and political debate, the hotwater-supply system of the capital city, Reykjavik, and smaller cities and towns is a proven success.
By now almost all the houses in Reykjavik and its suburbs are hooked up to the municipal hot-water system, which provides water at about 176 degrees F. to homes, schools, factories, and offices; in other words, to almost every building that can use hot water directly or for heating.
After circulating through houses the still warm water is often used to irrigate gardens or to heat greenhouses.
Large commercial greenhouses devoted to growing vegetables and flowers center around Hveragerthi, about 30 miles southeast of Reykjavik, but many homes also have smaller versions.
Drilling for hot water in Reykjavik began in 1928, and a pipeline reached some city houses by 1939. About half the homes were hooked up to the system by the end of World War II, and by 1972 it was in use almost across the board. Through the 1970s the system was extended to the suburbs, and similar systems are used, where practical, in the countryside.
When possible, rural boarding schools, many of which serve as hotels in the summer, are siteed near sources of underground hot water.
More visible than the heating system are Reykjavik's three public swimming pools, the largest of which is part of the city's major sports complex in Laugardalur.
For about $1 you can use the pool, sauna, hot spots, or try to sunbathe in the usually cool to cold outside air.
Not far from this modern facility is a reminder of times past called Thvottalaugar, or the washing springs.
Until this century city people and visiting seamen hauled their clothes here for washing. A statue by Icelandic sculptor Asmundur Sveinsson recalls the toil of the professional washerwomen.
More than a thousand years ago steam rising from Thvottalaugar may have been responsible for Reykjavik receiving its name. It means smoky bay, but this is only speculative.
As at Thvottalaugar, hot-water wells are found in many places, heating sections of rivers, lakes, or pools in volcanic craters and caves.
One very popular spot was Grjotagja, a pool in a cave near Myvatn. Since 1977, however, it has been closed because of a drastic increase in water temperature.
One of the most popular hot-water pools is in Akureyri, Iceland's "second city," which faces the Arctic Circle from just above 65 degrees north latitude. One early June night, while snow dusted the town briefly and covered the encircling mountains with white, steam billowed from the 86-degree outdoor pool.
It's quite an experience to float on the warm water, with only a cold nose, and gaze at the snow-covered mountains in a bright sun.