Lying like a teardrop in the Indian Ocean, Sri Lanka is an island that defies convention. Poised just six degrees above the equator, it’s less than 75,000 square kilometers in size. But it has enough wildlife to rival a vast continent, and it’s all down to its complicated climate and geography.

This film uncovers how all life on Sri Lanka centres on one precious resource: water. Unusually, two different monsoons visit the island each year, drenching the windswept coastal plains with weeks of torrential rain. For the rest of the year, the animals of the plains must endure months of drought. Elephants numbering in their hundreds gather on the shores of a vast lake in search of water. Bold Sri Lankan leopards stalk spotted deer visiting waterholes. Mugger crocodiles, confined within small pools, choose the dry season to mate. Beeeaters dig nesting tunnels in the dusty ground, and troops of toque macaques battle for status and hierarchy in the island’s ancient Buddhist monuments.

The plains rise sharply to the central highlands, where the peaks tower 2,000 metres above sea level. Up here, there’s no shortage of water all year round, and this drives diversity, just like in a rainforest. A staggering number of animals in these mysterious cloud forests are found nowhere else on earth. Purplefaced langur monkeys have grown particularly thick coats to deal with the extreme weather. Tiny pygmy lizards give birth to live young to protect them from the cold. Even within one rhododendron bush there are three unique species. These cold, wet mountains are what make Sri Lanka one of the most species rich islands on the planet.

As October approaches, the monsoon finally arrives, bringing abundant food, and relief for the animals that live on the plains.