BATU CAVES AND SARAWAK CHAMBERS 

It's so hard for me to rank these two since they are both amazing so i put them in the same spot.
Sarawak Chamber is known for being the world's largest underground chamber which can be found in Gunung Mulu National Park. he Sarawak Chamber measured 700 m (2,300 feet) long, 400 m (1,300 feet) wide and at least 70 m (230 feet) high.
Batu Caves is a limestone hill, which has a series of caves and cave temples, located in Gombak district. The cave is one of the most popular Hindu shrines outside India, dedicated to Lord Murugan. It is the focal point of Hindu festival of Thaipusam in Malaysia. The site is also well known for its numerous macaque monkeys. Rising almost 100 m above the ground, the Batu Caves temple complex consists of three main caves and a few smaller ones. Cathedral Cave or Temple Cave is the biggest.
About 12 kilometers north of Kuala Lumpur, in the district of Gombak, the Batu Caves are located. The name originates from the river of Sungai Batu, which runs alongside the hill. The limestone Hindu temples are built in the cave, which is about 400 meters deep and 100 meters high. Via a stairway of 272 steps you arrive at the entrance of the cave. It is a beautiful sight from the inside especially when rays of sunlight come in from the roof of the cave, but maybe even more so when you look at the city of Kuala Lumpur from that spot. The caves were turned into a place of worship in the early 19th century by an Indian merchant named K. Thamboosamy. Local traders and orang asli already knew of the caves for many centuries.

Temples in the caves

In 1891 the first temple was built in the cave. The large stairway to the temple was built in 1920. The Cathedral Cave is the largest cave, and is filled with altars. In 2006 the construction of a 42 meters high statue of Lord Murugan was completed, when we were there the construction had just started. To learn more about the history of the Batu Caves, you can rent a headset for RM13. You will hear all the relevant facts concerning the temple. Currently a cable car is being built that will transport visitors and temple devotees to the top of Batu Caves without having to walk up the 272 steps. It is expected to be ready for public in 2012.

Yearly festivals at the Caves

Every year a number of festivals/ceremonies take place in the cave, for example the Thaipusam celebration in January/February of the year (10th month of the Hindu calendar). It is a celebration for the youngest son of Shiva (Subramanian) and the unification of Pusan and the Brihaspati stars. More than a million Hindus come to this cave. In 2006 more than 1,500,000 Hindu pilgrims visited this celebration; this was one of the largest gatherings ever seen in history.
You might know the images of Hindus being hanged on hooks; self-punishment is an important part of Hinduism. The Hindus engage in self-punishment to force favors from the gods. To avoid the (touristic) crowds, it is advised to visit the cave on weekdays. In the weekends it is often filled to the brim with tourists. By the way, you have to watch out for the apes around the Batu Caves (macaques). These apes are extremely spoiled by tourists and become very aggressive towards the visitors because of this. They'll steal your bag, camera or food within a second, so always be alert.

How to get to the Caves

 The Caves are easily reachable from the centre of Kuala Lumpur. For RM20/RM25 you can take a taxi, when the taxi driver is driving on the meter it will be even cheaper. From the bus station Puduraya in Chinatown two busses also have a route to the Batu Caves, 11/11d and U6. The bus will take you to the Batu Caves in about 45 minutes. The easiest way is by taking the KTM Komuter train that goes from KL Sentral to Batu Caves station in less than 20 minutes. A ticket at KL Sentral will only cost you a few ringgits.
This cave contains the worlds largest natural underground chamber. Lubang Nasib Bagus (Sarawak Chamber) is more than 600m long, 400m wide and 100m high. The exact size of this chamber is not easy to determine, as a caver needs an hour to cross it, and it is still not completely explored. Headlamps are not able to light more than a per mille of the big hall, some photographs made with special equipment show parts of the chamber. They were made using special magnesium flashs.
Sarawak Chamber is only one room of this huge cavern. The whole passage has enormous size, as do many caves at this Park.
The mouth of the cavern is the resugence of a stream. Visitors follow the stream upwards, until they reach the cave. The stream normally springs 50m below the cave entrance, through the debris of a collapsed cave entrance. The cavers climb up to a colapsed part of the roof, then descend back to the river. Inside the cave, the spelunkers follow the stream upwards inside the cave to Sarawak Chamber.
Despite its size - or because of its size - the visit to the cave is not really difficult. But as most of the time the passage is filled with water, the ability to swim and apropriate clothes are essential. Because of the high temperature the trip is despite the water not very hard. But its a lot to walk, from the headquarter to cave entrance its a walk of about 4 hours. Often this is done with an overnight stay in a base camp 1 hour from the cave.
 It is rather difficult to determine the biggest chamber. First its a problem how to measure its dimensions, and then its a problem to decide which aspect of the survey data is most significant.
How do you measure the size of an underground chamber? In caves it is rather difficult to determine exact sizes, as surveying just follows a single line. You just get a sort of skeleton of the cave. The solution to measure surface and volume is to add the distance to walls, floor and ceiling. You measure to the wall as often as possible. In big chambers you may survey once along the wall. The height is determined using a thin rope and a gas filled balloon. This is also done as often as possible.