For sheer size, scale and variety, Indonesia is pretty much unbeatable. The country is just so enormous that nobody is really sure quite how big it is; there are between 13,000 and 17,000 islands. It's certainly the largest archipelago in the world, spreading over 5200km between the Asian mainland and Australia, all of it within the tropics and with huge areas of ocean separating the landmasses. Not surprisingly, Indonesia's ethnic, cultural and linguistic diversity is correspondingly great – the best estimate is of 500 languages and dialects used by around 200 million people.
Just across the water from East Java sits Bali, the longtime jewel in the crown of Indonesian tourism, a tiny island of elegant temples, verdant landscape and fine surf. The biggest resorts are the party towns of Kuta and adjacent Legian, with the more subdued beaches at Lovina and Candi Dasa appealing to travelers not hell-bent on raging nightlife. Most visitors also spend some time in Bali's cultural centre of Ubud, whose lifeblood continues to be painting, carving, dancing and music-making.
The islands east of Bali – collectively known as Nusa Tenggara – are now attracting crowds, particularly neighbouring Lombok, with its beautiful beaches and temples. East again, the chance of seeing the world's largest lizards, the Komodo dragons, draws travelers to Komodo and then it's an easy sail across to Flores which has great surfing, and the unforgettable coloured crater lakes of Keli Mutu. South of Flores, Sumba is famous for its intricate fabrics, grand funeral ceremonies and extraordinary annual ritual war, the pasola.
The whole archipelago is tropical, with temperatures at sea level always between 21°C and 33°C, although cooler in the mountains. In theory, the year divides into a wet and dry season, though it's often hard to tell the difference. In much of the country, November to April is the wet months (January and February the wettest) and May through to October are dry. However, in northern Sumatra, this pattern is effectively reversed. The peak tourist season is located between mid-June and mid-September and again over the Christmas and New Year season.