Of the fifty states in the United States, forty-nine are located on the mainland of North America. The other state is Hawaii, which consists of several islands in the middle of the Pacific Ocean. Hawaii is known as an especially beautiful and interesting place. The Hawaiian islands were formed by volcanic eruptions that pushed molten rock, called lava, above the surface of the ocean. Some of the islands no longer have any volcanic activity, but there are still active volcanoes on two Hawaiian islands, Oahu and the big island which is known simply as Hawaii. One of these volcanoes, Mauna Loa, still erupts sometimes, with spectacular explosions of lava. Another volcano, called Mauna Kea, is now dormant. These volcanoes are both very tall and reach over 4000 metres above sea level. The air above Mauna Kea is so clear and thin that scientists use the mountain as a base for observing the stars. The islands of Hawaii are located in the tropics, and they are known for their beautiful weather. The temperatures are usually in the range of 20 to 30 degrees Celsius, and the days are usually sunny. This weather allows people to enjoy swimming and surfing on the beautiful beaches of Hawaii. Despite the sunshine, most of the islands also receive enough rainfall to support many beautiful flowers and trees. The first people to live in Hawaii were Polynesian groups who arrived from other islands in the Pacific, well over 1000 years ago. The islands were visited by European explorers during the late eighteenth century. During the early nineteenth century, the islands became unified under a single king. However, during this time, many Hawaiians died from diseases that were brought by European and American visitors. The Hawaiian islands are excellent places for growing sugar cane and pineapples. In the late eighteenth century, some Americans began large farms, called plantations, in Hawaii. The Americans eventually gained control of the government, and Hawaii became a territory of the United States. The United States built a naval base on the island of Oahu, at Pearl Harbor. This base was attacked by Japan in 1941, but it was soon repaired. The naval base is still in use today. During the nineteenth and twentieth centuries, there was great demand for labour on the sugar and pineapple plantations. People came to Hawaii from many lands, and Hawaii became a place of many cultures. The native Hawaiians mixed with people from places such as Japan, China, Korea, the Philippines, Portugal, and Puerto Rico, as well as the mainland United States. Today, many Hawaiians can claim a diverse heritage. In 1959, Hawaii became the 50th state of the United States, with the city of Honolulu as its capital. Today, there are more than one million people in Hawaii, more than half of whom live in Honolulu. Each year, many more people visit Hawaii as tourists, to experience the beauty of these islands.