Khao Yai, Thailand's first national park, sprawls over four biodiversity-bursting provinces: Nakhon Nayok, Nakhon Ratchasima, Prachin Buri and Saraburi. It’s home to lakes, waterfalls, rock pools, prehistoric rainforests and a number of rare and endangered animals.

To protect Khao Yai National Park's 837 sq miles of prehistoric forest, visitors can only enter accompanied by a ranger — which is why, for my hike, I’ve been teamed up with Khun Bok, a cheerful 5ft-nothing local woman who’s been guiding visitors, tracking animals, preventing fires and catching poachers here for over 20 years.

Pulling a machete from her belt, Khun Bok hacks into the dead stump of what was once an 80ft eaglewood tree to let me smell the bark; its highly prized resin has a rich, woody, amber-like aroma and is used in the production of perfumes, incense and traditional Asian medicines. As one of the world’s most expensive commodities — top-grade eaglewood costs north of £80,000 per kilo — the illegal trade is pushing the critically endangered species to the brink of extinction. I couldn’t be more in awe of Khun Bok, working on the frontline, trying to save it.