First of three parts As the third millennium dawned, the light of the rising sun swept westward across the Pacific Ocean and the Bering Sea. It brought a gray half-light that crept slowly across the dark ice-locked wastes of northeast Asia. Farther south, the sun's fiery-orange disc rose majestically from the sea off the temperate coasts of East Asia; and along the tropical coast of Southeast Asia a swift transition conjured searing yellow sunlight from humid darkness.

From the Arctic to the tropics, the rising sun poured a path of light inland from Asia's rim. The new millennial dawn took many hours to complete its course across the vastness of this continent, until eventually it bathed the whole Asian region in light.

Asia and superlatives go hand in hand, for this is the largest and most diverse region on Earth. The continental portion extends 6,500 km from south to north, from latitude 1 North to 78 North, and 9,700 km from west to east, from 26 East to 170 West.

The islands of Malaysia and Indonesia extend the region well south of the Equator. Asia experiences the widest climatic extremes and supports the most varied flora and fauna on Earth. Greater in size than the Americas, more expansive than Europe and Africa together, Asia represents almost a third of the Earth's land area, more than 43 million sq. km.

Geologically speaking, Asia is, in fact, the youngest of the continents, consisting of several large fragments which have, over immense periods of time, accumulated in a series of collisions. The best known and most dramatic of these was the collision between the Indian platform and the southern edge of the continent that generated the many-ranked Himalayas and raised the Tibetan Plateau.

Traveling westward across the Pacific with the rising sun, modern Asia appears clearly delineated on the western horizon, where Pacific waves lap at the shores of Japan, and where the Bering Sea crashes against the shores of Maritime Siberia.

Yet viewed from where the same sun sets, Asia appears more nebulous. There, the mountainous wall of the Urals and the deep channel of the Bosphorus, though distinct physical borders themselves, are not clearly linked. Travel east into Asia from Europe and cultural and natural history features blur and blend in a steady transition toward the less and less familiar.

Even within Asia, the differences from one region to the next are so great as to render generalizations almost meaningless; suffice it to say that Asia is phenomenally diverse. However it is defined, not only is it enormous, but it harbors a breathtaking range of natural geographical features and life forms. If you are excited by the tallest, oldest, highest, deepest, look no further. Asia has them all: from Arctic tundra and taiga to tropical rain forests; humid evergreen and temperate forest regions; savannas, deserts and deciduous forests; steppes, montane and alpine regions.

Wildlife abounds in Asia: from the minute, multicolored hyperthermophilic bacteria in the rich volcanic hot springs of Kamchatka to the rainbow-colored reef fish playing hide and seek with their predators in the warm waters bathing Indonesia's islands; from the high-flying demoiselle cranes that migrate each year over the Himalayas to the depth-plumbing sperm whales that feed along the ocean depths off the Kurile Islands; from common and widespread species of the north, such as the red fox and Asian chipmunk to the rare and unique species endemic to the isolated islands of the southeast, such as the proboscis monkeys of Borneo and the gibbons of Java. Each region of Asia supports its own special fauna and flora.

Twenty of the highest peaks in the world, all over 7,000 meters, are in Asia. Sagarmatha, Chomolungma or Mount Everest, by whichever name it is known, stands as tall as they come (8,848 meters), elevated slowly over millions of years by tectonic subduction and consequent powerful uplifting forces. From the highest peak, Asia plunges to some of the greatest depths on Earth, reaching more than 10,000 meters in the Ramapo Deep off Japan.

Seven of the world's longest rivers, all of them more than 4,400 km long, flow across Asia. The longest, the Chang Jiang or Yangtze, stretches some 6,390 km through China. Length, however, is not everything. It is the Yenisey-Angara River, flowing into the Arctic Ocean, that is Asia's largest, for its drainage area covers 2.7 million sq. km, virtually the same land area as the whole of Argentina.

The geological forces that shape the land of Asia trigger events that drive the climate too. The annual monsoon winds sweep a curtain of rain across southern Asia, but this life-giving rain is turned back by the great wall of the Himalayas.

The inexorable glissade of the tectonic plate which the Indian subcontinent rode into the southern edge of Asia about 50 million years ago has pushed ancient sea beds sky-high into the jet stream. These ever-growing mountains are a massive weather machine. They block the force of the southern monsoon, creating a vast rain-shadow to the north, and the 19 great rivers that drain them carry moisture across nearly a third of the Asian continent.

While considering Asia's water supply, let us not forget that the largest inland body of saltwater is also in Asia. The Caspian Sea in the far west of Asia covers 371,000 sq. km, so big it could cover all of Malaysia.

Although the Caspian is deep, reaching a maximum depth of 1,024 meters, it is outdone by another Asian lake, one of the oldest in the world, and the deepest freshwater lake of them all.

Lake Baikal, in Siberia, holds about 20 percent of the world's liquid fresh water, and reaches an abyssal depth of more than 1,600 meters. As isolated in its own way as any of the myriad offshore islands of Southeast and East Asia, Lake Baikal is, in its isolation, a living laboratory for evolution, for speciation and adaptive radiation.