The "Pirates of Justice" -- a costumed crew of activists -- are raising a literal warning flag against cruise ships on which they say workers are overworked, underpaid and sometimes abused.

The group will converge tomorrow at 12 p.m. to stage a flash mob at Vancouver's Canada Place, using theatrical tactics to increase attention.

"Although this is a very serious issue, we've still got a sense of humour and it's a good way to connect with people who might not normally be involved in this sort of thing," said spokesperson Craig "Blackbeard" Greenfield. He said last year's event attracted about 100 people.

This year, the pirates are focusing on Carnival Cruise Line vessels hosting Olympic security personnel.

The activists say that Canadian forces and the RCMP have commissioned three ships -- the MS Statendem, the MS Oosterdam and the Carnival Elation -- at a cost of $76 million from Carnival Cruise Line, a company that activists accuse of maintaining exploitative working conditions.

Cruise ship worker Jessie Campbell, who worked on the MS Stantendam, claimed that some staff members work 12-hour shifts, seven days a week but don't complain for fear of losing their jobs.

"I've been really burdened lately with the unfair treatment of the Indonesian and Filipino workers onboard," said Campbell in a release. "The dining room staff are only paid $50 per month because they are not getting a cut from the gratuity."

Research by the International Transport Workers' Federation, a cruise-industry watchdog, highlights, among other things, the prevalence of insecure, short-term contracts; illegal agent fees; low wages; poor management practices, including gender and racial discrimination; and resistance to unionization.

But Carnival spokesperson Jennifer de la Cruz painted a different picture of her company, highlighting employee access to unpaid accommodation, medical and dental care, and retirement plans.

"We have more than 100 different nationalities represented among our crew who have gravitated to cruise ship jobs because in most instances they represent superior earnings opportunities versus what they can make in their home countries," Cruz told the Globe and Mail, adding that the activist's cause is not legitimate.

Greenfield wasn't surprised: "They basically wrote us off as a stunt but didn't deny our allegations," he said. "They could have easily said 'that's wrong, they're not paid $50 a month,' but they didn't do that."

Organizers have set up a Facebook event page, where there are 63 confirmed attendees at time of writing. The flash mob is being advertised as a family friendly event.