Pick a popular spot for teens and you're likely to see them: E-cigarettes, being passed around like a bag of chips.
A 2015 state survey estimated that roughly 1 in 4 Hawaii teens used e-cigarettes, slightly higher than the national average.
But their use is believed to have grown since then, judging by what's happening on and near Hawaii high school campuses.
"I started vaping since I was seventh grade," said a 10th grade student who Hawaii News Now is not identifying.
A friend of his did as well.
"I stopped for an entire year. Then more and more people started vaping," the second student said. "I'll just go back into that too."
Their attitude appears to be an indication of what's happening with teens across the state -- ones who attend both public and private schools. Many admit to vaping -- the inhaling and exhaling of vapor produced by an e-cigarette -- on school property.
"A lot of my friends vape," one teen said.
At least once a week, McKinley principal Ron Okamura says, a member of his staff catches kids puffing on an e-cig or possessing the device on campus.
"If they want to flaunt it, they pay the price for it. We confiscate it," he said.
Department of Education disciplinary rules treat e-cigarettes the same as tobacco products, as contraband items. Punishments vary from school to school, ranging from detentions to suspensions.
"We are seeing a rise of kids having the product on them," Radford High School principal James Sunday said. "You don't smell it. If they do it in the bathroom or areas that we might not see, it's hard to smell and investigate the problem."
Without a way to single out offenders, there's no way of knowing how many students are getting away with it, Sunday says.
At St. Francis School in Manoa, Sister Joan of Arc Souza has not had to deal with the problem yet, but vows to be tough on repeat offenders.
"Expulsion! Because I just don't believe this is not going to hurt them. It is," she says.
Vaping away from school grounds is another matter. Hawaii's legal age to use or purchase e-cigs is 21, but many teens openly ignore the law.
Sherri Vega's son did -- at least before she caught him.
"For them to do things that aren't right, the only thing you can do is guide them," she said
"The thing that I don't understand is, you've got to be 21 to purchase these things," Okamura said. "How do they get it? Who knows."
When asked where he got his e-liquids, a teen we spoke too said it wasn't hard.
"I buy it from the store," he said.
Other vaping teens say they get it from older siblings or friends who buy them. Reputable E-cig shops ask for identification and warn that it's a crime to buy the devices for an underage person.
The state, however, doesn't keep track of every merchant who sells the devices, so it's impossible to check up on them. The University of Hawaii's Office of Public Health Studies is still trying to compile a list.
"Part of the E-cigarette tax bill that's in play right now at the legislature is to require anybody that's selling e-cigarettes to pull a tobacco permit and license," said Jessica Yamauchi, of the Hawaii Public Health Institute.
Those concerned about keeping vaping products out of teenagers' hands also think the state should close a loophole -- one that allows minors to lie about their age when buying vaping products online.
A spokesperson for the Honolulu Police Department says that if an officer issues a citation to a teenager caught with an E-cig, the fine is $10 for the first offense and $50 for each subsequent offense.