The non-profit organisation Signi Zoekhonden, based in the Netherlands, has deployed a team of six people and four dogs to the island, the BBC reports.
The mother of the missing 19-year-old, Debbie Duncan, said the new search was made possible through the “generosity” of people donating to a crowdfunding page.
The apprentice bricklayer from Lancashire in north-west England was last heard from on June 17 after he attended a music festival on Tenerife.
He called his travel companion Lucy Law to say he was lost and attempting to walk back to their accommodation, but needed water.
Law said Slater was wearing only shorts and a T-shirt, inappropriate for both the warm daytime weather and cold nightly lows.
Authorities on the Spanish territory launched an extensive search for him, combing the Canary Islands off the coast of Africa with helicopters, search dogs and drones.
Police scoured the rough terrain around the village of Masca, where Slater stayed after a night out, but called off the official search after 12 days when there was no sign of him.
Signi Zoekhonden has about 20 years experience in searching for missing people and contacted the teenager’s family after reading about the case.
One of its volunteer searchers, Marieke Krans, said the group will also deploy drones in the search, subject to flight permission being granted by local officials.
“We are very committed to come and we are confident in the dogs and in ourselves,” she said.
“Our dogs are trained to find people, both alive or dead, and have more skills. They can search underwater, and up mountains, whatever it may be.
“They are really creative and that means there is more we can do. We will go where the dogs lead us.”
Kraus said the work of Signi Zoekhonden includes searching for survivors of earthquakes and other natural disasters.
The volunteers plan to liaise with local authorities and spend about five days on a search mission.
