Sean Thomas felt curiously at home in Java: he found a volcano, a walled city and his local supermarket manager
Twenty miles north of the ancient Javanese capital of Jogjakarta, 500 miles east of the Asian entrepot of Jakarta, halfway up Gunung Merapi - the sacred Javanese "firemountain" - I walked into a small, dark, fly- blown bar and ran into the manager of my local Sainsbury's, in Islington.

I hadn't planned this; the world just keeps getting smaller. And it was pretty lucky, in a way. For ages I had wondered why Sainsbury's hadn't knocked through a door to the car park. Here, in this lamplit, wood-panelled bar - full of the aromas of frying chilli and fresh coconut milk, wafting in from the streetside eating-stalls (warungs) - I got the chance to find out.

The brooding volcano under which we drank and chatted is reputed to be the most active spot in the furiously volcanic archipelago that is Indonesia. She more than lives up to her fearsome reputation. The manager of our hotel (the Vogel, clean and spartan, 8000 rupiah, or four pounds, a night), had told us that to climb the Old Lady we'd have to be up pretty early. Struggling out of bed before dawn we donned our hiking-boots and rucksacks and set off in the direction of the wispy summit. We got as far as the roadblock. Gunung Merapi had woken up with a nasty hangover; she was angrily puffing out clouds of lethal sulphur gas, and coughing up the odd half- ton lava bomb - and I suspect she was in no mood to see a couple of scruffy Brits crawling all over her. Three-quarters of a mile from the main ascent the police turned us back, for our own safety. We didn't really mind: standing on the special viewing-platform we could hear the rumbles of imminent eruption. It was enough.

We hailed one of the Indonesian public minibuses (bemos), which are cheap, packed, slow, and plentiful, and travelled into the serene, sprawling, historical city of Jogjakarta ("Jogja" to locals and aficionados). Jogja is the backpacking capital of Java, where discerning Aussies, and others doing the Asian trails tend to congregate, in preference to madcap Jakarta, or touristy Bali. The food here is cheap and good; the hotels are cheap and quite good; there's a legion of services that have sprung up to cater for the non-package traveller - airline agencies, change houses, authentic craft and batik shops. Most of these are situated in the Sosro area, near the station.

South of Sosro lies the ancient centre of the city-state, the sultan's court, or kraton. Here between 1750 and 1950 the gamelan-playing, dagger- wearing upper classes of Java honed their culture to an exquisite edge; the place still has a slightly superior, aristocratic air. The sultan's palace and parliament - his real power was taken away in the 1940s, after the Indonesians threw off the Dutch yoke - is a disappointing sight. It looks like your grandmother's bungalow just outside Newquay, and the gaudy railings and multi-coloured chandeliers are unmistakably nouveau. The surrounding area is more interesting - a walled-off royal city wherein live the courtiers who spend their days glorifying the sultan and his lovely sultana. Lots of the dwellings in this area have cages full of songbirds hanging outside the front door. Walking down one of the flowery alleyways the music of the birds fills your ears - a sweet, liquid lullaby.

The absence of obvious religious buildings in the walled city exposes one of the peculiarities of Indonesian life. The country - all 1,900,000 square miles of it - is said to be 90 per cent Muslim. But Indonesia has adopted a very mild form of the faith, in deference to its Christian and animist peoples, and its Buddhist background. Take a half-hour bemo-ride from central Jogja to Borobodur, and you can see how deeply rooted the old faith is. Borobodur is a huge Buddhist temple that sits amidst the rainy green lushness of coffee fields like an enormous grey cowpat. Carved in the eighth century, this tufa-stone temple is said to be the third greatest Buddhist monument in the whole world, after Cambodia's Angkor Wat and Burma's Pagan. I don't know about the bronze-medal rating: it's certainly a calmingly spiritual place. I spent a whole day marvelling at Borobodur's delicate sculptures, climbing its vertiginous steps, dodging its sapphire-blue dragonflies, and watching the thunder and lightning play across the dark mountain-scape to the west.

Between Jogjakarta and Jakarta lies the real Java: green, beautiful, volcanic, superfertile, chocker with people.

Everywhere you look - if you aren't looking at palm groves and banyan trees and water buffaloes and torrential rivers of milk-chocolate brown water - you can see people tilling the fields in black upside-down-saucer hats, or picking tea, or whipping cows, or bicycling home from work: from the silversmiths, or the woodcarvers, or the Japanese motorbike factory.