It's only when we get to the tiny, seemingly deserted hilltop village that we think is the nearest to the Boom festival site, and the sun has set, that we realise we forgot to print out the exact directions. We pull over in a cobbled parking space off a little winding street and wonder what to do. Beyond the village the landscape is pitch black. There are none of the usual indications that a festival is going on nearby – no signs, no long car queues.
We roll down the windows, letting in warm air and the sound of cicadas, and I lean out, hoping a bassy beat will give us a clue. We wait. Then a dilapidated junk-ship of a campervan pulls out ahead, psychedelic flower patterns painted on its sides, a trail of techno leaking in its wake.
"Follow that van!" says my friend Anna – there's no doubt it's headed the same way.
Boom is not a natural choice for me. Primarily a psytrance festival, hosting big names from the scene (in 2010, Eat Static, Gus Till, and Zen Lemonade played; for 2012, Ace Ventura, X-Dream, Ajja and Manmademan are among the main acts), it is also heavily "not just about the music" – raising consciousness, living outside the dominant culture and spiritual social activism are all key aims. I'm rather dubious about all this stuff but my buddy Anna is a fan, and anyway the festival has more to recommend it than the hard dance line-up.
Held in the middle of the Portuguese nowhere, every other year in August (on the full moon of course), the setting, beside a dazzling lake at Idanha-a-Nova, three hours' drive north-east from Lisbon is simply incredible. Guaranteed sunshine is another bonus: we will not be bringing wellies, nor our cagoules, and to make the most of the trip we're going to a surf camp on the coast for a few days afterwards.
At the festival entrance, at the end of a bumpy, sandy road, huge sculptural gates welcome us into a shallow valley, and we're soon among the torch-wielding stragglers snaking along a lakeside path with our camping gear, past little candle-lit cafes offering chai and Sagres beer, towards the lights of the festival ground. And what a ground it is, a grassy grove of colourful tents, fantastical sculptures, fires, lights and lasers. There are no white burger vans and commercial outlets: here organic food stalls are made from wood, carved into mystical shapes, and we never really have to queue for anything.
Hammering tent pegs into bone-dry ground proves almost impossible and once the tent is up we realise we've pitched it over an ants' nest and have to move it. Then we throw ourselves into the music. Despite my lack of love for psytrance, the beat has a physical effect and forces me to dance. People are going wild, but after a few hours we hit the sack. It's only then that I realise we've camped far too close to the action – I can actually feel the beat through the ground, despite my ear plugs – and that at Boom the music plays round the clock. At least we've made it to bed in the hours of darkness. Most revellers wait until daylight to crash and are faced with trying to sleep in 45C heat. For that reason (and a few others) I suspect many just go without.
After an amble between the organic food stalls the next morning and a nice little post-breakfast dance in one of the tents, we go swimming in the lake and watch the fun from the water. It's simply too hot to be out of it (in both respects I'd say, though plenty are having a go). And there are rather a lot of naked people, including one man doing eye-catching handstands. Psychedelic body paint is popular, hundreds wear sarongs and bikinis and a hell of a lot accessorise with dreadlocks. Everyone is friendly and there is a real mix of nationalities, but there is an overwhelming sense that this is a Scene – they call it a tribe, and it seems quite a lot of attendees live this feathers-in-the-hair alternative lifestyle full time. The festival is incredibly green, with a grey water recycling system, compost toilets, generators powered on waste vegetable oil, solar panels and a windmill.
The raving continues in the big tents all day, with irrigation systems spraying the sweaty throng with a fine mist of cold water. We drink smoothies in the shade at various cafes and pop into the Inner Visions gallery of psychedelic art, quite clearly designed for an audience on acid. Mind altering substances would probably also help at the talks, which range from aura reading, soul pulling and lucid dreaming to "Art, Drugs and God" and "Why Bad Sound is Disrespectful to Our Divine Nature".
We sit in on a lecture about the benefits of a raw food diet, by an Englishwoman who feeds her kids only raw fruit, vegetables and nut milk, and home-schools them according to her own syllabus because "who knows what knowledge the future world will require?". Maybe it's just heatstroke but I start to feel irate.
Another session, on breaking down the frontiers between men and women through movement, is more entertaining and has us stifling giggles. Those who opt to join in find themselves before a small audience, exploring the boundaries of sexuality together through (bad) dance, while blindfolded. The men go first, swaying uncertainly in their blindfolds and waiting to be chosen by one of the circling women who must then attempt to move them about in a sensual way. They lumber about awkwardly, and I am certain 100% of them are imagining their partner is the sexy girl in the silver bikini, though 99% look unabashedly crestfallen when they pull their blindfolds down.
The early evening is beautiful. We watch the sun set over the lake, eat a really good veggie Thai green curry (the food is one of the best things about Boom) and discover an amazing musical pagoda sculpture made from scrap metal, with built-in chairs where you can enjoy the strange jangles and tinkles created by the breeze moving various gongs and bells. An Indian guru with flowing robes, turban and a long beard stops to listen on his way to give a lecture; a skinny boy with dreadlocks plays a flute. We drink sangria and dance for a while, but the sun has killed us. Much to Anna's disappointment she is too exhausted to rave it up till dawn.
We meet some people planning to stay at the festival site for 10 days, which sounds good to Anna, who has fallen for Boom. I can't exactly say the same; the music just isn't varied enough for me, it is disrespectul to my divine nature. Perhaps I need longer, or to have camped way away from the event further around the lake, as others have been clever enough to do. Perhaps it was because I failed to attend the talk on "overcoming self-sabotage", but whatever the reason, when the time comes for us to head to the coast, the opportunity to escape the loud, pounding music, the oppressive heat and to some extent, the oppressive culture, mean that is when I feel most happy and free.
• Boom is held every two years. The next one is 28 July-4 August (boomfestival.org/boom2012). Tickets cost €160. Tap Portugal provided flights to Lisbon (flytap.com). Flights cost from £152 return. For information on the region near Boom, Centro Portugal, see visitcentro.com. Car hire was provided by Car Trawler (cartrawler.com)
