Lombok lies 8 degrees south of the equator and stretches some 80km east to west and about the same distance north to south. It is dominated by the second highest mountain in Indonesia, GUNUNG RINJANI, which soars to 3726m. It has a large caldera with a crater lake, Segara Anak, 600m below the rim, and a new volcanic cone which has formed in the center. Rinjani last erupted in 1994, and evidence of this can be seen in the fresh lava and yellow sulphur around the inner cone.

Central Lombok, to the south of Rinjani is similar to Bali, with rich alluvial plains and fields irrigated by water flowing from the mountains. In the far south and east it is drier, with scrubby, barren hills. This area gets little rain and often has droughts which can last for months. In recent years, several dams have been built, so the abundant rain-fall of the wet season can be retained for irrigation throughout the year.

In Lombok's dry season - from June to September - the heat can be scorching. At night, particularly at higher elevations, the temperature can drop so much a sweater and light jacket are necessary. The wet season extends from October and January the wettest months.

The 19th century naturalist Sir Alfred Wallace (1822 - 1913) observe great differences in fauna between Bali and Lombok - as great as the differences between Africa and South America. In particular. He postulated that during the ice ages when sea levels were lower, animals could have moved by land from what is now mainland Asia all the way to Bali, but the deep Lombok strait would always have been a barrier. Thus he drew a line between Bali and Lombok, which he believed market the biological  division between Asia and Austaralia.

Plant life, on the other hand, does not display such a sharp division, but there is a gradual transition from predominantly Asian rainforest species to mostly Australian plants like eucalypts and acacias, which are better  suited to long dry periods. This is associated with the lower rainfall as one moves east of Java. Environmental differences, including those in the natural vegetation, are now thought to provide a better explanation of the distribution of animal species than Wallace's theory about limits to their original migrations.

Modern bio-geographers do recognize a distinction between Asian and Australian fauna, but the boundary between the regions is regarded as much fuzzier than Wallace's line. This transitional zone between Asia and Australia is nevertheless referred to as "WALACEA"