It is supposed to be the trip of a lifetime for teens — and the Toronto-based youth travel company running the excursions promises they will be safe and supervised.

To parents, S-Trip's spring break and grad trips offer the chance for their teens to have fun, explore local culture and volunteer in countries like Mexico, the Dominican Republic and Cuba.

And they often pay a steep markup, sometimes double the holiday's actual cost.

But a CBC Marketplace investigation reveals the reality is very different, with underage binge drinking and hard partying. And often the staff — sometimes only a few years older than the students themselves — don't do much to stop the party.

"Hey, we want some pussy. Hey, we want some pussy," S-Trip staff members chant with students, arms linked, on the beach.

Another staff member leads a game where students pass a ball from person to person, without using their hands. "This may be a first for some of you, but you're going to have balls on your tits," the staffer says.

CBC Marketplace: S-Trip vs. YouTube0:43

Much of the behaviour is documented on social media in dozens of videos uploaded by the students themselves. Clips show students chugging liquor, drunkenly climbing trees and wrestling on balconies. Some are grabbing girls or drawing on their breasts.

"It's absolutely deplorable what they allow on these trips," says one former S-Trip leader, who quit because the behaviour made him so uncomfortable.

The staff member spoke with Marketplace on condition of anonymity, saying the contract he signed with S-Trip prohibits him from speaking publicly about the trips.

In response to the Marketplace investigation, the company says it is reviewing its policies, doubling the amount of training required by staff and doubling the number of staff for its summer 2017 trips.

Rules disregarded

Student Trip was founded in 1976 by two high school teachers. In 2001, the company changed its name to S-Trip and began expanding, opening offices in the Dominican Republic and Boston.

For three years running starting in 2011, S-Trip was named one of the fastest-growing companies in Canada by Canadian Business magazine, selling thousands of vacations to teens each year.

S-Trip drinking

While S-Trip's marketing materials emphasize safety, supervision and the opportunities to volunteer and experience a different culture, multiple YouTube videos depict binge drinking and hard partying. (YouTube)

S-Trip markets the trips as more than just a vacation — it's all about the overall experience and the trips come at a premium price as a result.

Marketplace checked how much you'd pay if you independently booked the same resort for the same dates. The S-Trip price was often double.

A trip to one Cuban resort last July, for example, would have cost less than $1,000 per person if booked through a popular travel website. Going with S-Trip, however, was $1,955 per student.

S-Trip says students vacationing with the company are governed by a strict code of conduct that must be signed by all young travellers and their parents. A video on the company website shows S-Trip's CEO saying that if students break the rules, they will be sent home.

Code-of-conduct questions

But Marketplace visited one of the resorts during an S-Trip holiday and found the code of conduct was often disregarded. For example, quiet hours are supposed to begin at 10 p.m., but Marketplace producers found that is also when the official S-Trip party began.

"The guys here are dicks," one student told Marketplace. "They all try to get you drunk and then they just take advantage of you."

While alcohol is permitted for students 18 and older — the legal drinking age in Cuba — Marketplace found students of all ages were often drunk. And other rules, such as those requiring students to be sober while swimming in the pool or ocean, were not enforced.

S-Trip website

S-Trip said that the behaviour documented by Marketplace would be 'grounds to dismiss staff and send home travellers.' (Marketplace)

These vacations are, first and foremost, party trips, the former S-Trip trip leader says.

"It's shocking that more students aren't harmed or at least come forward about some of the things that they do or see while on these trips," he says, calling the S-Trip code of conduct "a farce."

"It's a lie to make money. Bottom line."

During the trip he worked on, the former leader said staff members were told not to intervene in some cases of underage drinking. He said he also saw staff make inappropriate comments about young girls and encourage them to engage in sexually charged behaviour.

While S-Trip's marketing material states the company carefully screens "travel veterans that have backgrounds like teaching, coaching, student leadership, event planning and our own past travellers," the former trip leader says he and other staffers were formally considered volunteers and paid only a modest honorarium.

First-time trip leaders are paid $150 for the week, although their flights and accommodations are covered, according to a staff manual acquired by Marketplace.

Teen travel 'uniquely challenging': S-Trip

S-Trip declined an on-camera interview with Marketplace but said in emailed statements that "the conduct identified by CBC Marketplace is of extreme concern to us."

The behaviour documented by Marketplace, the company says, would be "grounds to dismiss staff and send home travellers."

S-Trip pool

While alcohol is permitted for students 18 and older, Marketplace found students of all ages were often drunk. And other rules, such as those requiring students to be sober while swimming in the pool or the ocean, were not enforced. (YouTube)

S-Trip also said it has launched a review of its policies, is doubling the training hours required by staff and is doubling the number of staff per trip for summer 2017.

"The overwhelming majority of our travellers comply with the code of conduct and have a fun and safe experience. Similarly, our staff are conscientious, highly trained, subjected to careful reviews and, in nearly all instances, provide excellent support and service to travellers," the statement says.

"Nevertheless, designing and supervising trips for travellers in this age group can be uniquely challenging. Misconduct and mistakes do occur. We try to be honest and direct about that fact — with our staff, with travellers and with their parents."

Two per cent of students get warnings, the company says, and one in 600 get sent home.

Injuries and lawsuits

Heavy drinking on S-Trip holidays has got students in trouble before.

In 2011, a 17-year-old student was drunk during a party when he fell two storeys from a hotel balcony in Puerto Vallarta, Mexico. He hit the concrete and suffered a traumatic brain injury.

A lawsuit filed in 2013 alleges that while the student was too young to be legally permitted alcohol at the resort, there was little supervision and nothing to prevent him from freely obtaining alcohol.

S-Trip dark room

Some principals have sent letters to parents, warning that S-Trip vacations are not school sanctioned. (YouTube)

The case is ongoing, though S-Trip said in a statement to Marketplace that it has since introduced additional protocols concerning balcony safety. At the Cuban resort, Marketplace saw stickers on balcony doors advising students to exercise caution.

In another lawsuit, a 17-year-old student, also too young to be drinking based on S-Trip's rules, fell into a large hole while drunk, slicing open her leg. That case is currently in mediation, S-Trip says.

'Virtually no adult supervision'

Some high school principals have tried to raise a red flag for parents who might think S-Trip holidays are either associated with or endorsed by their schools.

"A number of serious issues are brought to my attention each and every year," one principal's letter to parents reads. "Students will not be supervised by my staff … in any way. I want to repeat that this is not a school trip. Students have virtually no adult supervision.

"Please exercise caution."

'Supervised' student trips not exactly as advertised1:38

Based on a Marketplace investigation by Greg Sadler, Melissa Mancini and Charlsie Agro