The team are from the National Protected Area Authority (NPAA) and are tasked with guarding the rainforest from encroaching illegal miners and loggers.
But with just 62 wardens to cover some 14,000 hectares (35,000 acres), it's an arduous game of cat and mouse.
"The devastation is getting worse every day," said Sheku Jusu, 36, the regional NPAA conservation officer.
"When we are patrolling in the forest, every day we come across new sites that they have just started operating."
Jusu's words became a reality no more than 30 minutes into the rangers' ascent, when a pile of fresh sand on the riverbank indicated that mining had just taken place.
"This is very recent, this was an hour or two ago," said Bockarie Kowa, 48, the NPAA regional coordinator.
"While we are sleeping, they come."
By mid-morning it was already 27 degrees Celsius (80 Fahrenheit) with 96 percent humidity, and the group faced a long trek on unforgiving terrain.
Kambui Hills Forest Reserve lies in Sierra Leone's Eastern Province -– an area bordering Guinea and Liberia with large reserves of gold, rutile and diamonds.
It was the trade of so-called blood diamonds which largely financed the country's brutal 11-year civil war, leaving some 120,000 people dead.
But along the rocky riverbanks of the Kambui forest, the miners are predominantly searching for gold.
Mineral-rich Sierra Leone is one of the poorest countries in the world, with the rangers blaming economic hardship for the escalating exploitation of the natural landscape.
Economic incentive
The scars of land excavation were evident along the patrol route, with orange earth and stones piled next to the occasional deep pit of an abandoned gold mine.
Rangers said that mining was causing trees to be uprooted, which were then being exploited by illegal loggers.
Midway through the patrol, a break in the dense tree cover gave way to a vast expanse littered with felled trees.
Sierra Leone has one of the highest deforestation rates in the world according to the Environmental Performance Index -- put together by Yale and Columbia universities.
Since 2000, the country has lost over 35 percent of its total tree cover and 14 percent of its humid primary forests —- some of the world's most ecologically significant habitats -– according to Global Forest Watch, an online monitoring platform.
Kambui itself is home to a diverse range of mammal species including the western chimpanzee, the black and white colobus monkey, the brush-tailed porcupine, and Maxwell's duiker -- a small antelope.
The lush forest also provides a habitat for threatened birds such as the white-necked rockfowl.
Over the past decade and a half, the government has stepped up its conservation efforts, with the creation of the NPAA in 2012 and the Ministry of Environment and Climate Change in 2018.
A diplomatic source, who requested anonymity due to their position, told AFP that economic interests largely fuelled Sierra Leone's environmental drive -- with international climate finance supporting forest communities, and eco-tourism providing a much-needed cash boost.
But poor coordination between government ministries, enforcement problems, and a lack of community involvement in protecting the landscapes means that deforestation continues on a large scale, they added.
'Spoil it along the way'
Part of the NPAA's mission is to engage local communities on the importance of preserving Sierra Leone's abundant flora and fauna.
But the unarmed rangers said that interactions with those they found in the forest could quickly turn sour.
"Some of them are armed... they have axes, they have machetes. So if you try to arrest them, they chase you," said conservation officer Jusu.
Moments after spotting the riverside excavation site, the rangers apprehended two young miners who offered little resistance as their sand-covered hands were placed in cuffs.
Regional coordinator Kowa said that such cases were usually sent to the police, after which they could face jail.
Mohamed, a 23-year-old sciences student, said he had been gold mining for two years and had little choice.
"The job is really dangerous, but we have to get money for sustenance," he explained.
Conservation officer Jusu was well aware of the challenges in trying to change mindsets in an area where vast natural resources go hand in hand with extreme economic hardship.
"Some of these trees are very important, but (the miners) do not know the importance," he said.
"They spoil it along the way."
