An ex-child soldier who has spent years risking his life to fight illegal mining and wildlife poaching has been given a prestigious award.
The Goldman prize for park ranger Rodrigue Mugaruka Katembo, from the Democratic Republic of Congo, honours "environmental defenders" worldwide.
It comes as new analysis shows more environmental activists were killed in the last year than ever before.
Mr Katembo is one of several winners of this year's award.
He has been tortured and imprisoned and has suffered mock executions in his work defending the Virunga National Park. The park is home to one quarter of the world's critically endangered mountain gorillas.
Mr Katembo told the BBC, "You cannot do this work think you are going to earn money, because that will not happen. You have to do this because you have the heart and the passion to make a real change."
The Goldman Environmental Prize honours individuals who go to extreme lengths to protect the environment. Indeed, previous winners of the award were recently murdered.
In harm's way
Mr Katembo's life is in constant danger. In the last two decades, at least 140 of his ranger colleagues have been killed. Armed poachers and militias operating within the park outnumber the protectors by 10 to one.
He wore secret cameras and microphones to expose corrupt officials intent on helping the British oil company, Soco International, to drill for oil in the park. His fight was the focus of the Emmy award-winning film, "Virunga".
The pressure forced Soco to abandon its plans. However Mr Katembo told the BBC that he feared this might be temporary because no agreement has been signed. "The fight is still going on. The instability in the DRC means that Soco will see some openings to corrupt people and to come back in to the park," he said.
After the director of Virunga was gunned down in a failed assassination attempt in 2014, Mr Katembo was moved to the second-largest national park in the DRC. He has already closed down several illegal mines in Upemba, but says the security situation is even worse.
"This park is home to the last zebras of the Congo and one of the last population of elephants in the region. However, the rangers don't even have one vehicle," he says.
According to the monitoring organisation Global Witness, last year looks like becoming the deadliest on record for environmentalists. Their official report will come out in July. "Once again mining seems set to head the list of the bloodiest sectors to oppose, although we are also analysing what appears to be a marked increase in threats and murders of park rangers across Africa," the campaign group said.
The BBC spoke to another prize-winner who won the award for fighting mining companies - this time in India. Prafulla Samantara helped to stop a $2bn mining project on ancestral lands in Odisha.
He led the Dongria Kondh tribe to a landmark victory in the Supreme Court over Vedanta Resources Ltd. The UK-based company wanted to extract millions of tons of iron ore from a sanctuary in the Niyamgiri Hills where the tribe co-exists with rare wildlife including Bengal tigers, elephants and leopards.
The environmentalist, who has been kidnapped and attacked on numerous occasions, describes it as a "victory of the people's movement and people's rights over the resources".
Samantara's legal triumph is the first time that indigenous people has been given the right to decide on mining proposals on their sacred lands. It sets a precedent for the whole of India, empowering village councils to make the final decision about mining activities in their region.
He said that, "in India 60 million people have been displaced over the last 60 years because of big projects such as mining and dams. The crux of the problem is that the people are not consulted."
"My mission is that we strive to not allow 'mindless mining'. There needs to be a balance between ecology, nature and human beings or development."
The other winners are:
Wendy Bowman, Australia: The octogenarian stopped a multinational mining company from taking her family farm and protected her community in Hunter Vally from further pollution and environmental destruction.
Mark Lopez, United States: He persuaded the state of California to provide comprehensive lead testing and to clean up a community in East Los Angeles contaminated by a battery smelter that had polluted the area for decades.
Rodrigo Tot, Guatemala: An indigenous leader in Guatemala's Agua Caliente, he achieved a landmark court decision that ordered the government to issue land titles to the Q'eqchi people and kept nickel mining from his community.
Uros Macerl, Slovenia: An organic farmer, he rallied support to stop a cement kiln from co-incinerating petcoke with hazardous industrial waste.