Established in the 19th century, the rain forest section of the Singapore Botanics Gardens was already one of the last "virgin" tracts of Lowland Evergreen Rain Forest (LERF) in Singapore. As described by the Botanic Gardens' catalogue in 1899:
"With one or two exceptions, this is the only piece of original jungle left on the island…. It gives the visitors some idea of the wonderful richness of tropical vegetation."
LERF has been the dominant vegetation in Singapore due to its climate and prior to the rapid development brought by the colonial British, mainland Singapore was mostly covered by LERF, which provided its residents with rattan, resin and other forest products which the island was known for trading. Today, this 6-hectare rain forest is one of the crown jewels of the Botanic Gardens, hosting over 310 species of plants in their natural habitat. The complex ecological system of climbers, tall emergent trees and ferns which are the defining features of LERF can still be seen here in the rain forest.
Many of the majestic timber trees of Singapore: the jelutongs, kempas and the dipterocarpacaeas (two-winged seed trees, like the meranti) still stand in the forest, shading the forest floors from sunlight. The climbers, like the liane and rattan, scale these trees to reach for the precious sunlight blocked by the verdant canopy of the rain forest. Besides its diversity of flora, the forest also plays host to a variety of animals. Try to spot the nimble Plantain Squirrel, the most abundant small mammal in Singapore as it leaps from branch to branch. Listen to the loud calls of the large Malayan cicadas which cling on the the trunks of the trees and chirp to one another. Perhaps the occasional shrill call of the banded woodpecker will break the cicada choir, and if you're observant, you might just catch the Greater Racquet-tailed Drongo and its eponymous long tail behind it as it flies in the canopy. Other birds, in addition to the common garden birds, which are worth looking out for here are the Collared Scops Owl (which was spotted while planting the cache, not too far from GZ), the Jambu Fruit Dove, Drongo Cuckoo and, if you're very, very lucky, the rare and elusive Hooded Pitta.
As for the cache itself, it is placed under the boardwalk built for visitors. You should be able to reach the cache from the boardwalk without stepping off it, or climbing the railings. In fact, I would strongly discourage you from doing so as the forest floor is home to many flora and fauna endangered in Singapore, and stepping off the boardwalk will disturb the ecosystem. You are looking for a small brown plastic container placed on the metal supports of the railing, above ground but under the boardwalk. Due to the thick canopy, the GPSr could only record the coordinates to an accuracy of the 10 - 15 metres. I've tried my best to average the readings, but I anticipate that your GPSr will run into the same problems. Again, I reiterate, do not step off the boardwalk even if your GPSr indicates otherwise.