When a barge carrying tons of heavy equipment overturned in the heart of a killer whale sanctuary last summer, environmentalists warned of the damage a diesel slick would wreak on the fragile ecosystem.

Now the B.C. government has taken a first step to understanding the extent of the damage to Robson Bight, releasing a fascinating video that shows decaying crushed trucks, bobcats, and containers of industrial fluid.

Many of the vehicles have been crushed, said Jennifer Lash of the Living Oceans Society, who has seen the video.

But a truck carrying 10,000 litres of diesel fuel looks untouched -- meaning that fuel is a "ticking time bomb" if anything happens to that truck, said Lash.

"In general, it looks like you could get in there and drive it off the bottom of the ocean," she said.

"We've got a ticking time bomb at the bottom of the ocean," she said. "We have to act on this as quick as we can."

On August 20, 2007 the barge, carrying 11 pieces of equipment, entered the protected area of Robson Bight Ecological Reserve.

It overturned, dumping that equipment into the water and leaving a diesel slick that was several kilometres long.

According to B.C.'s Ministry of Environment, the footage shows that the sunken equipment is mostly upright and relatively undamaged.

The government says it has to review the footage, adding that the material underground isn't likely to decay any further.

The footage was obtained by B.C.-based Nuytco, a company that specializes in undersea expeditions with submersibles. It surveyed the wreckage in detail over several days.

Diesel can be harmful to ocean life, especially to whales, who will swim and ingest the hydrocarbons without realizing it, showing problems later.