Detailed background information, which covers the formation of the caves, cave ecology and some of the unique animals which live in them, the bird's nest industry, and the archaeology of the Great Cave, as well as some of the myths and legends of the people using the cave, is provided separately. Please refer to the Background section.
The trail from the Traders Cave enters into a covered walkway, just before the West Mouth of the Great Cave. It's a bit hard to get much of a feel for the size of the Great Cave from here, but there are views down into the extensive archaeological excavations.
These excavations were the most important at Niah, and include the so-called "Hell Trench", which is covered and runs just below and parallel to the Boardwalk. This is where the 43,000 year-old Deep Skull was found. Behind it, extending into the cave, is an area known as "the Cemetery", containing hundreds of burial sites, dating from a range of periods over the past 30,000 years. The location has also yielded important and interesting information about long-extinct animal species and environmental changes in the area. For more detail on the archaeology, please refer to the Niah Archaeology & Prehistory background page.
The covered boardwalk soon ends, and you now start to get a true appreciation for the sheer size of the Great Cave - it is in fact one of the biggest caves in the world (not far behind Mulu's Deer Cave and Sarawak Chamber). The West Mouth is about 250m wide and over 60m high.
The next think you will probably notice is the smell of guano, and the noise from thousands of bats and swiftlets high above. The smell is quite strong and sickly, but not overpowering.
Once you have got over the initial awe (and smell), and your eyes have adjusted, you will notice the impossibly thin wooden poles leading up into the dizzying heights. These are climbed by brave birdsnest collectors, who may spend a whole week up the top without coming down, collecting the prized birds nests. The poles are made of highly durable ironwood (belian), and are joined with wooden pegs - no iron nails are used. Some of these poles may be very old (possibly up to a couple of centuries) as birds-nest have probably been collected here for 1500 years. The poles are fixed by wedging them (and other supports) into cracks and holes in the ceiling. (See the Cave Ecology section for more information about birds nest collecting.)
The building inside the cave in front of you was built by the Sarawak Museum. It was built on the spot of an earlier building used by the archaeological team in the 1950s, which burned down. Just in front of the hut is an offering table where a ceremony is performed to mark the beginning of the nest-collecting season (See the Niah Peoples, History and Culture background page for more information on the ceremony.)
You will also notice that the ceiling and walls of the cave are a bright green colour - this is caused by a type of algae, which probably feeds on the nutrients from the guano, and uses the light coming in the cave mouth. There are relatively few stalagtites and stalagmites inside the cave, except at the cave mouth itself.
The trail follows the fence protecting the archaeological site, along the left wall of the cave. It climbs steadily up massive and ancient piles of guano (in places 8 to 9 metres deep along here!), past some pits where it had been quarried in the past. You can see the small black nests of some of the swiftlets which contributed to this smelly mountain, on some of the lower sections of the ceiling - and you can hear plenty of them higher up. (See the Cave Ecology section for more information about the swiftlets, guano and guano quarrying.)
The cave passage is split here, with a massive central column separating the two halves - this column was in essense a large island in the river as it cut its way through the mountain, making the caves.
At the top of the climb, you get views through to the other side of the mountain - and many more poles. The passage in front is called Lubang Tulang, meaning "Bone Cave", named for the human bones and found there. In 1961, Barbara Harrisson noted that hundreds of bodies were placed in this part of the cave as part of funerary processes. Remains of items such as Chinese coins, porcelain, and bronze and iron objects indicated that the people buried there were probably rich, most likely from birds nest trade.
The boardwalk turns right into a gap in the pillar separating the two halves of the cave, and descends steeply into a cave called Lubang Bengkok, or "Bent Cave". This soon opens out into a wide and very open area called Lubang Padang, or "Field Cave". The ceiling of Lubang Padang goes all the way up to the top of the mountain, where a couple of holes let in sunlight. A big section of rock called Bukit Terayang projects up into the cave. Beams of light projecting from the holes in the ceiling onto this small hill are quite spectacular in the afternoons.
On your right, there is a junction with the second branch of the boardwalk, which leads back into the West Mouth. (Take this route back now if you've had enough - its not as much of a climb as going back the same way. The trail is described below.)
A shelter built just up and on the right of the boardwalk provides a spot to take a break and enjoy the views from Bukit Terayang down to another cave mouth opposite - this is the mouth of Lubang Hangus or "Burnt Cave".
From the padang, the boardwalk descends steeply again into a narrow and very dark passage (you'll need your torch/flashlight in here). The walls here are completely smooth and clean. This passage is called Lubang Bulan or "Moon Cave", named for an effect of the light where a smooth and almost perfectly round passage opens out into the light of the Padang - resembling the shape and luminosity of a full moon.
The boardwalk proceeds ahead into Lubang Gan Kira. This section of the cave is less frequently visited or disturbed than other parts because swiftlets do not nest in here. For that reason, it is often possible to see some of the interesting cave inhabitants here, such as the giant carniverous cave crickets. This area also has a relatively low ceiling, allowing you to see a couple of the bat species from closer up. (See the Niah Cave Ecology background page for more details on the critters living here.)
The boardwalk through here is fairly even and relatively straight, descending gently towards the mouth of Lubang Gua Kira (literally, "Right Cave Passage") - the back mouth of the Great Cave, which leads out to the trail to the Painted Cave. Close to the mouth, the cave opens out, and there is a bit of rubble and a number of large boulders where small creatures may hide.
The Return Leg to the West Mouth
The trail in the Great Cave includes a loop, which goes around the great central column. On the way back, it is easier to complete the loop - and it provides a bit of variety. The climb from the junction (see above) is quite steep, but there are great views of the West Mouth looking down from the top - a great vantage point for photos. There is also a small shelter and bench a little way down, where you can catch your breath.