BC Ferries is reminding customers not to drink or do drugs onboard after police were called out 15 times to ferry terminals to deal with suspected impaired passengers in the month of June.

"What we have had over the last month is quite a spike in some of these incidents," said Deborah Marshall who speaks for BC Ferries.

"Everybody should have a good time in the summer, but just keep the beer in the cooler until you get to the campground."

BC Ferries has a "zero tolerance policy" for anyone using drugs or alcohol on its property, as well as "the unacceptable conduct that can be associated with impairment," according to a release.

The reminder comes at the start of the busy summer travel season, with extra sailings added ahead of the Canada Day holiday.

"We do see this type of incident occur in the summertime, particularly when the weather is nice and warm," said Marshall.

Impaired driving laws apply to operating vehicles at BC Ferries terminals and on ships, just as they do on the road, the release stated.