Inside the dangerous process that goes into collecting one of the most expensive food products in the world

Edible bird's nests, often called the "Caviar of the East," are one of the most expensive food products in the world. While an average nest can retail for around $2,500 per kilogram, some can go for as much as $10,000 per kilogram. Bird's nest soup is commonly found in high-end restaurants in China, but the ingredients can also be found at some food markets in the region.

Created by the swallow-like swiftlet and built out of a protein-rich secretion from the bird's saliva, the nests are coveted in Chinese culture for their medical and rejuvenating benefits. But another part of what makes the prized nests so expensive is the dangerous collection and laborious cleaning process they require. Inspired by a documentary on the subject, British photographer Andrew Newey decided to travel to the Madai Caves in Malaysia, where the local Ida'an people climb up as high as 500 feet just to collect the nests.

Here's a look at the fascinating process, from the towering heights the men scale to the tiny knives and tweezers they use to pick the nests out.