Waisak in Borobudur
Waisak is, for Indonesian Buddhists, a celebration of the Buddha's birth, death and enlightenment.
On the full moon that marks the eve of the festival, the massive mandala of Borobudur in Magelang becomes the focus for a solemn procession in the moonlight. Thousands of Buddhists – monks, nuns, and laypeople alike – walk from Mendut Temple, carrying a holy fire and a container of holy water to an altar on the west side of Borobudur.
After circling three times clockwise around Borobudur and receiving blessings from holy Buddhist gurus, the crowd releases about a thousand sky lanterns, with a wish for enlightenment to spread across humankind.
Festival date: 19 May
Bali Arts Festival
The culture-crazy island of Bali becomes the focal point for one of Indonesia's biggest arts festivals every July. First established in 1979 as “the basic forum for the growth of our love of the arts,” as expressed by Bali's then-Governor Ida Bagus Mantra, the celebration has grown by leaps and bounds in the ensuing decades, now bringing together artists and disciplines from not just Bali, but from all over Indonesia.
On the second Saturday of June every year, the festival kicks off at the Werdi Budaya Art Center in Denpasar, with any number of cultural events taking place on the grounds, from barong dances to sendratari (Balinese ballet) recitals. Other highlights include documentary screenings, cooking exhibitions, arts exhibits, and live gamelan orchestras.
Festival date: 16 June - 14 July
Yadnya Kasada on Bromo
The Tenggerese who live in the farmlands surrounding Mount Bromo trace their descent to Majapahit-era Hindus who fled to the mountains after the coming of Islam. They believe that their ancestors, a couple named Roro Anteng and Joko Seger, ended years of childlessness by successfully petitioning the gods for children. After 24 children, the gods decreed, the couple had to throw the 25th into the volcano crater as an offering. (Read about climbing active volcanoes in Indonesia.)
Today's Tenggerese do not descend to human sacrifice, but on the 14th day of the Kasada month, they congregate to the Bromo crater to sacrifice other things: money, live chickens, flowers and food. (Non-Hindu locals aren't as reverent; they clamber down the crater to pick up the sacrifices intended for the gods!)
Festival date: 17-18 July
Dieng Cultural Festival
The children of the mist-shrouded Dieng plateau in Central Java share a gift from the ancestors: upon reaching a certain age, their straight hair naturally forms into dreadlocks. When this happens, the children wait till August, when their hair is ritually shaven off in a ceremonial collectively called the Ruwatan Anak Gimbal.
For the Dieng locals, the ceremony is an opportunity to celebrate – the 8th-century Dieng Temple complex, the site of the hair shaving ceremony, becomes the focus for several days of feasting, shadow play performances, fireworks, and the release of traditional lanterns.
Festival date: 1-4 August
Baliem Valley Festival
The Baliem Valley Festival shines a spotlight on an off-the-beaten-path part of the country, Indonesian Papua. To get to Baliem Valley, you'll need to climb up the Jayawijaya Mountains on the island of New Guinea, stopping when you reach a magnificent valley up in the clouds.
During the Festival, Baliem Valley's tribes put on their best traditional garb, and perform Papuan cultural traditions, including pig-racing and spear-throwing contests. The biggest event – a mock war held over two days – involves about fifty warriors in full battle dress, fighting it out as the strains of Pikon music wafts through the air.
Festival date: 7-9 August
Lake Toba Festival
For five days every December, the Lake Toba Festival puts North Sumatra's cultural gifts on display for the world to see. The native Batak of Lake Toba throw a feast as thanksgiving for the year's blessings, including displays of Batak opera, tortor dance, and exhibitions of ulos weaving and boat races.
The placid Lake Toba belies its violent history; formerly ground zero for a massive volcanic explosion over 70,000 years ago, the lake and its Samosir island now serve as a home for North Sumatra's Bataks, who fish and trade around the lake. Today, Lake Toba is the largest lake in Southeast Asia, and one of its deepest.
Festival date: December