IMAGINE a sun-soaked island with only 12 people per square kilometre, with beaches, rainforest, desert, remote hiking trails, historic sites, active volcanoes and high mountains where, for several months of the year, you can actually ski under the tropical sun. This is the Big Island of Hawaii, also known as the Orchid Isle, because more varieties of this exotic flower are grown here than anywhere else in the world. The Hawaii Volcanoes National Park has 250 kilometres of uncrowded trails, varying from half-hour strolls to three-day treks. The trails wind past steaming craters, through yawning lava tubes and into jungles of fern and ohia. Nevertheless, they are wellmarked and safe. Particularly awesome is Devastation Trail where sepulchral tree trunks sprout like charred tombstones in a cooled lava stream. For back-packers the park provides A-frame cabins equipped with bedding, kitchens, utensils and fireplaces. Even in the tropicsthe nights are cold at 2,000 metres. Linking the Kalapana and Kilauea sections of Volcanoes National Park is the Chain of Craters Road, built in 1965. Since then lava from the Mauna Ulu eruptions of 1969-74 has oozed over sections of asphalt. Over the past 20 years the size of the Big Islandhas increased by more than 80 hectares due to flowing lava. The National Park Visitor Centre has maps and guidebooks on the 900 square kilometres park, which was established in 1916. Kilauea Caldera and Mauna Loa are completely separate and are considered to be two of the world's most active volcanoes. Kilauea's activity is evident everywhere in the park, but the most dramatic scenes are from Crater Rim Drive, misted along its 18 kilometre length by steaming, sulphuric vent-holes. At 1,100 metres on the volcano's rim is Volcano House, a comfortable mountain lodge that has been serving visitors since 1846 when it was a grass shack. Afternoon tea or an evening cocktail on the inn's balcony afford a breathtaking view of the great Kilauea caldera. The 3,900 metre Mauna Loa and her big sister the 3,950 metre Mauna Kea are the Big Island's crowning glories. Measured from its base in fact, Mauna Kea is the tallest mountain in the world, soaring over 9,000 metres from the ocean floor. The second largest city in the State of Hawaii (Honolulu on the island of Oahu is number one) is Hilo, the City of Rainbows, on the east coast of the Big Island. The city derives its nickname from a nearby waterfall, Rainbow Falls, where spectacular coloured light prisms dance in the spray of cascading water. Not far away at Honomu, the 122 metre Akaka Falls is the state's most accessible and tallest sheer-drop waterfall and an ideal spot for picnics. In the Hilo area the acres of lavender orchids and the greenhouses filled with hundreds of species of the flower are well worth seeing. A guide is always on hand to explain orchid culture. Among the most photographed spots in Hawaii are the black sand beaches at Punaluu and Kaimu. Spewing from the hubs of hell, the hot lava hit the ocean, exploded and became pulverised. Years of pounding surf have reduced the black cinders to a fine sand that does not stain skin or clothing. The Big Island is the only region of the United States that commercially produces coffee. It is grown on the sunny slopes of Kona, after which the coffee is named, on the island's west coast. Adjacent to the coffee farms is Kealakelua Bay where Pacific explorer Captain James Cook, arriving at festival time, was mistaken for the God Lono by the natives. The same natives, later learning that Cook was not Lono, put him to death. The southern tip of the Big Island, Ka Lae, is the most southerly point in the United States. Here a hiking trail leads to a green sand beach, a delightfully secluded emerald strand that derives its colour from volcanic olivine (magnesium iron silicate).