For most of the year, New Yorker Lori Levine is deeply ensconced in her urban life and job at an advertising agency.

But when it comes to those hard-earned vacation days, she spends them a world apart from her everyday routine. A flip through Levine's vacation albums reveal snapshots of her working alongside locals in South Africa at a lion sanctuary, in a Rwandan rhino preserve or at a Cambodian elephant rescue.

Levine is hardly alone in her large-hearted, far-flung approach to outreach. The multi-billion-dollar volunteer tourism industry in Latin America, Asia and Africa has been expanding over the last two decades. Nancy Gard McGehee, a professor at Virginia Tech, estimated in a report that people are collectively spending up to two billion dollars a year on volunteer trips overseas.

Levine was made aware of volunteer tourism — or voluntourism — after she caught a news report detailing the conservation efforts of a South African animal sanctuary called Lion Whisperer. That night she wrote to the nonprofit organization to ask if there was any way she could help.

Three weeks later, Levine boarded a plane bound for South Africa for her very first trip not only to Africa but to an animal sanctuary. The total cost of the trip was about $2,500 (roughly $1,500 for airfare and $300 to $400 a week for room and board). That's no small cost for giving of your time, but for Levine the experience and knowledge gained proved priceless.

Lion Whisperer founder Kevin Richardson started the sanctuary to protect African lions from being raised to fuel the tourism business. Richardson had worked in a lion park which bred lion cubs for tourists who would pay top dollar to pet and pose with cubs for pictures. When the cubs mature, many are sold off to "canned hunt" ranges where tourists pay up to $100,000 to trophy hunt these lions who were not raised in the wild, so are relatively easy prey.

A large part of the trip is focused on raising awareness about the plight of the lions and the multimillion-dollar industry for lion cubs. During her two and a half weeks at the sanctuary, Levine learned how to safely work with the lions and the sanctuary's other residents, including hyenas and black leopards. Levine was also instructed on how to prepare meat for the lions' meals and clean the pens.

The payoff of all the daily labor is the proximity to these majestic animals. "I love the quietness of watching the animals," says Levine — who grew up on a horse farm in central New Jersey. As a tourist, she notes that she would never have had access to observe the lions with such intimacy. "You'd never see how they eat or how they fight," she says. "In our downtime, we would photograph them."

Along with the animals, Levine also cherishes the wisdom and friendship imparted by the sanctuary workers who have dedicated — and sometimes risked — their lives to help these animals. Not to mention the first-hand political education gained from being in a place and working with the locals.

Immersive education is an essential element of voluntourism. When the Toronto-based Operation Groundswell sends its clients — mainly students aged 18 to 24 — out on its 40-day Thailand/Cambodia program, the organization encourages "local change makers and activists" to guide their volunteers. The group's mission statement for its various trips led around the world is "to create a more equitable, just and sustainable world through the power of travel."

"We want to take the lead from local community organizations because they are the ones who live and work there and understand the scope of the issues," says Justine Abigail Yu, the organization's communications and marketing director.

On one level, an assignment might be to help a group, such as an elephant refuge to clean up a bamboo area for the animals. Yet visitors will also be learning about the rehabilitation process for Asian elephants and broader environmental concerns.

No matter what type of volunteer tourism you choose, it's key to do your research and know that the animal-focused wildlife organizations are legitimate.

"Responsible tourism is fairly new," says Dave Bouskill, a travel writer who, along with his wife Deb, writes the travel blog The Planet D. In Sri Lanka, for example, the couple found a resort that donates part of its fee to a leopard project which helps local residents build fences and pens for their livestock to prevent them from being attacked by leopards. In turn, the effort helps save the leopard population.

Sometimes it takes getting an up-close view of things before you can even properly define "responsible."

Take the popular photo-op of sitting astride an elephant. While volunteering at the Elephant Valley Project in Cambodia, Levine learned that riding Asian elephants can cause the animals to develop arthritis or crooked backs.

This sanctuary for aging and endangered elephants is a nonprofit that provides local elephant owners money to replace what they might have earned from the animal's forced labor and then offers a home for the elephant at their reserve. "The owner is happy, the elephant is happy and the sanctuary is happy," Levine explains.

Choose your destination

Five wildlife and animal conservation-focused volunteer organizations to consider:

Lion Whisperer

South African lion preserve focused on stemming the rapid decline of African lions due to factors such as habitat loss and illegal hunting.

Imire Rhino & Wildlife Conservation

A preservation dedicated to the breeding of rhinos, care of African elephants, environmental sustainability and community building in Zimbabwe.

Elephant Valley Project

Asian elephant sanctuary in Cambodia that aims to improve the health and welfare of captive elephants, work to conserve the environment and the local people who work with the animals.

Save Elephant Foundation

Asian elephant sanctuary in Thailand that rescues and cares for injured and overworked elephants and returns them to a natural habitat.

The Ape Alliance

Founded in 1996, this international coalition works for the conservation and welfare of apes. Several of its member organizations have volunteer programs including a chimpanzee rescue center in Cameroon in West-Central Africa and one for endangered orangutan in Indonesia.