With its rim of evergreen magnolia trees and prickly malnourished lawns, Cathedral Park appears to be little more than an unremarkable square at the corner of Dunsmuir and Richards streets. Though on the surface this inner-city green space resembles so many others-an aging water feature with chipped blue paint and three low-pressure spouts, too much cement, and circa-Expo 86 metalwork-its Bruno Freschi-designed elements serve a dual purpose. The water is part of an elaborate cooling system; the cement columns house huge exhaust fans. Cathedral Park is actually the street-level lid of a subterranean power station the size of an office building, feeding the insatiable electrical appetite of the core's countless high-rises, shops, and hotels. The park and its underground grid serve as the inspiration and site of the Intermission Artists Society's open-air event called Mercury Theatre III: The Sub-Station next Friday night (September 9).

As part of the Pacific Association of Artist Run Centres' (PAARC) sixth annual gallery hop, SWARM 6, which happens next Thursday (September 8) in Mount Pleasant before heading downtown for Friday, Intermission put out a call for performance artists, visual artists, and musicians to explore this "giant electric heart" and the hidden underworld of Vancouver. The result is submissions that span from the literal to the abstract.

"One person did still shots of electrical lines around the city, so it's very literal," says Julie Gendron, at Cathedral Park with Intermission colleagues Khan Lee and Marianne Bos. "Another has to do with the internal system of a computer. It's an animation and it's very abstract."

A live installation of sight and sound, Mercury Theatre III: The Sub-Station marks this artist-run collective's (www.inter-mission.org/) third contribution to SWARM. The group's event has grown from a modest undertaking to a collaborative effort of 45 artists and musicians from across Canada and the United States. Two on-site VJs will mix stills and live feed, projecting images onto two large screens suspended above the main concourse of the park. Working independently of each other but with the same images, the VJs will each adjust the meaning and context of the projections. The resulting image streams will be interpreted aurally by a 14-member orchestra during the event, which runs from 9 to 11:30 on Friday night. Performance artists-including Mathew Wing demonstrating a stylized kung fu and a group called 20-Watt that will be snaking through the crowd in a cloth tunnel while wearing miners' lamps-will be offering their own take on the Sub-Station theme.

"The video and the music are all improvised, so the artists need to listen to each other and look at the screen," says Gendron, a 32-year-old visual artist. "That means no one artist can really be prominent over another-no egos. It's a live soundscape, meaning the sound will change according to what's being shown."

Using instruments that range from laptops to guitars and samplers to sitars, many of the musicians have never performed for a crowd and all have only been jamming together for a couple of months in preparation for the event.

Bos, project manager of the Sub-Station installation, and a contributing artist and musician, stresses the collaborative, organic nature of the project. "It's about the ability to listen and figure out what kind of sounds everybody can create and what is needed within that soundscape," she says.

Artists working collaboratively are at the core of this project and it's an ethos that drives artist-run centres throughout the city. This is the reason, according to SWARM 6 executive committee member Lance Blomgren, PAARC is presenting the increasingly popular two-night event for the sixth time. "It came out of PAARC wanting to show off artist-run centres," says Blomgren, codirector of the Helen Pitt Gallery. "SWARM...is a chance where different kinds of galleries that often don't have much interaction do interact briefly for those two nights."

For Bos, Sub-Station is also about inviting an audience to explore its own hidden underworlds, to listen to the beat of their electric hearts. "It changes your perception not only of the city but possibly of yourself, and that might create other possibilities and other ideas."