Punch and Judy would never approve of this

The London International Mime Festival has a problem, and that, in a word, is its name. Silent beret-wearers fingering invisible walls - that's still what mime suggests to most people. The truth is that the LIMF, in more than two decades, has rarely presented mime in that fashion. And you'd be pushed to describe many of this year's 19 presentations as mime of any kind.

The London International Mime Festival has a problem, and that, in a word, is its name. Silent beret-wearers fingering invisible walls - that's still what mime suggests to most people. The truth is that the LIMF, in more than two decades, has rarely presented mime in that fashion. And you'd be pushed to describe many of this year's 19 presentations as mime of any kind.

The territory is now broader and wilder than labels allow, straying to the furthest frontiers of physical comedy, and mapping byways of puppetry so dark and strange that children should keep well clear. This Saturday's opening fanfare comes from the Moscow company BlackSkyWhite - a disquieting swirl of lights, giant marionettes, clockwork spider bats, and pounding industrial sound inspired by expressionist films.

Spanish performance artist La Ribot perhaps comes closer to traditional notions of the speechless form. But she's hardly a mime, more a nude art exhibit, with her droll tableaux vivants, each piece available for sale. Will her pubic hair be blue or electric pink this year? Only visitors to the South London Gallery will know.

But much of this year's line-up extends beyond quick-fire visual gags. Take, for example, Symphonie Fantastique, a work of abstract puppetry set to a major orchestral work inside a giant fish tank. This is a far cry from Punch and Judy. Swathes of fabric, feathers, glitter, mirrors, dyes, fishing lures, fibre-optic cables and Super 8 film are manipulated in 500 gallons of water to match Hector Berlioz's "dream fever" score.

The show was created by the American, Basil Twist, for a four-week run in New York's SoHo. It ended up selling out for a year and a half - which tells you more about its phantasmagoric appeal than adjectives ever could. Drug enthusiasts have likened it to an LSD trip. Others have called it "music for the eyes". Perhaps the show's most remarkable feature - aside from its medium - is that it doesn't involve a human likeness in any form. The four puppeteers (who get very wet) are hidden, and though Berlioz's music famously comes with its own narrative, Twist prefers to tell his own abstract tale of swirl, drift, pounce and float. It must be the first work of theatre where air bubbles get a laugh.

"For me," says Twist, "the big idea is not that it's underwater, but that it's non-representational. What the water does is remove you from reality, allow the imagination to drift free. There's no context for the water, no Little Mermaid or anything." How did he come up with the idea? "I always imagined I would see something like this in the course of my puppetry studies," he says. "But I never did. So I had to make it up. What I like is that everyone sees something different in it. I get people coming up to me saying: 'I loved the fireworks' or, 'I loved the bit with the hats'." Twist's show uses hundreds of objects, but certainly no hats.

The mind's eye gets another serious work-out in Shunt's offering, The Ballad of Bobby François, sited under a railway arch at London Bridge. Here the mood is distinctly macabre. Who remembers the 1972 air crash when a rugby team's charter plane came down in the Andes? Certainly anyone who saw Shunt's show at the Edinburgh Festival. Actually, "saw" isn't quite the word. "Did" is more like it; for punters unwittingly find themselves fellow passengers on the doomed Fairchild F-227. And the crash becomes horribly real. Gemma Brockiss, a cast member, says people often swear and scream at the critical moment. "It's only done with sound and lights," she explains, "but people do take the crash subjectively. Imminent death is hard to get your head round."

Famously, few of the Andes crash victims survived the 70-day wait for help, and those that did survived by eating the dead. Shunt's ambitious piece asks spectators to consider the etiquette of survival and the implications of cannibalism in civilised society. "There is humour," encourages Brockiss. "But it's pretty bleak. What interests us is the extremity, and what brings people to that point. It's the imaginative journey that matters."

Festival directors take note. Journeys of the mind: is there a more accurate title in there somewhere?

LIMF: various London venues, 13 to 27 January. Call 020 7636 5661 for more information