A Vancouver Island man is sharing a cautionary tale for boaters as they head out to the Celebration of Light fireworks show, demonstrating just how quickly a fun evening on the water can turn tragic.

Marshall Patterson says he loves boats, but lately he's been avoiding the water. Last August, he was boating on Lake Cowichan, doing about 30 kilometres per hour, when he ran into another boat carrying nine teenagers.

"It was a harsh impact," he said. "I started hearing the screams and the chaos and your whole heart and stomach goes ‘Oh, no,' and your worst fear comes true."

Four of the teenagers needed stitches, and one had a concussion so serious she claims she couldn't work for a year. Patterson, who was bloodied in the accident, says he just didn't see the other boat.

He was fined $1,000. The teens' lawyer, Chris Considine, has also filed a lawsuit against Patterson, claiming he was negligent.

"The consequences ranged from soft tissue injuries, such as bruises, abrasions, and cuts, to closed head injuries. For some of my clients, the consequences have been significant," Considine said.

Patterson says the teen's boat should have been better lit, and wants all boaters to be more cautious.

"It hasn't been fun. Instead of being here doing an interview, I'd rather be out on the lake. But it's the way it's all worked out," he said.

Boaters are advised to have their lights on, to go slow, and to watch what's going on around them – because others might not.

With a report from CTV British Columbia's Jon Woodward