Traveling in a day from Kota Kinabalu, the capital of Sabah state in Malaysia to Bandar Seri Begawan, Brunei, or vice-versa, can be easily done by flying, driving, taking boats or by catching buses or taxis. Of course, the level of comfort and how much you end up spending will depend on what mode you choose.
Getting from Kota Kinabalu to Bandar Seri Begawan, the capital of Brunei, can be seen as one leg of the "Borneo Overland Trail" which can be covered continuously between Tawau at the southeastern tip of Sabah, and Kuching at the southwestern end of Sarawak. Both states are part of Malaysian Borneo but the trail also requires you to pass through the expensive sultanate of Brunei which lies more or less in between the two states.
The stretch covered by this leg can be both challenging and fascinating; challenging because it involves traveling through some of the more remote corners of Sarawak and Sabah where the roads may not be at their best. Traffic is light and public transport connections require a little more time to work out. The trip can also be fascinating because you will get to see what it's like to live in one of the richest countries in the world.
This itinerary basically just shows you the way to get from Kota Kinabalu to Bandar Seri Begawan within a day and does not leave you much time for any diversions (thankfully, there are not too many, although visiting the Pulau Tiga Park, Klias Wetlands, white-water rafting on the Padas River and even exploring to forests of the Ulu Temburong National Park in Brunei are some interesting ones) and opportunities to experience the relaxed atmosphere of the small remote towns along the way. Give it one or two more days and you will get to feel the places a little more.
There isn't really that much for which to prepare as the route goes through many towns where you will be able to get food and drinks -- and accommodation if you get stranded -- without any problems. If you are driving, just make sure that your car is in good condition as there are many stretches where you'll have to wait for a while before you can thumb a lift to the nearest mechanic.
As the route brings you across state and international borders (it's wonderful for passport stamp collecting -- a maximum eight if you choose the correct route), make sure you satisfy the necessary immigration requirements. Check with Brunei | Get in and
Malaysia | Get in for details. If you need visas, make sure you get multiple entry ones as you'll be hopping in and out of Brunei and Malaysia several times.
The thing you'll probably need the most is patience -- to wait for minivans or buses to show up, to wait for them to fill up, to wait for them to complete their rounds in town just to get more passengers, to wait out connections which don't work out, to wait out breakdowns, to wait in lines at ferry crossings and immigration checkpoints. Once you have mastered that, you'll see a pretty interesting Sabah rural life along the way.
Besides the two end-points of this itinerary, there are several places where you can join or leave the overland trail from Kota Kinabalu to Bandar Seri Begawan.
Kota Kinabalu: This is the start of the itinerary and you can get here by air, road and all modes of public transport from other parts of Sabah. See Kota Kinabalu's Get in section for details.
Beaufort: This is the next major town where you can join the trail and there are several options:
One of the most interesting ways to reach Beaufort is to take the train from Tenom in the interior of Sabah. Tenom can be reached by road from Kota Kinabalu and this allows you to have a much more interesting alternative to the direct Kota Kinabalu-Beaufort stretch. The train snakes along the Padas River and you can also go for a bit of white-water rafting here before rejoining the trail. However, you will not likely be able to make it to Bandar Seri Begawan in a day if you use this alternative.
You can also reach Beaufort from Labuan, which can be reached from Kota Kinabalu by boat. From Labuan, you can take a ferry to Menumbok where you can catch minivans to Beaufort. This is another alternative to the direct Kota Kinabalu-Beaufort leg of the journey. Using this alternative route may also prevent you from making it to Brunei in a day.
Lawas: The first big town you hit once entering Sarawak, Lawas provides you with a very interesting opportunity to leave the trail completely and head up to Ba Kelalan to visit the Kelabit Highlands. An ex-logging road links Lawas to Ba Kelalan and private four-wheel drives and trucks take passengers to the highlands.
Limbang: From Limbang, you can take the Headhunter's Trail and head to the Gunung Mulu National Park. You can then fly out of the park to Miri, allowing you an alternative route that bypasses expensive Brunei.
The fastest and most comfortable, but also the most expensive, Royal Brunei Airlines  operates one or two daily roundtrip services between Kota Kinabalu and Bandar Seri Begawan. The flight takes about 40 minutes. Malaysia Airlines  also operates three flights per week in both directions between Kota Kinabalu and Bandar Seri Begawan. Air Asia has also started to fly the route at discounted prices
By road all the way even in your own car is taxing, taking anything between eight and ten hours. A lot of time is spent waiting at border checkpoints -- there are no less than eight checkpoints to go through -- and some of them, especially those with Brunei, can get very busy with long lines during weekends and holidays. There are also two ferry crossings which can take time too. The road condition is generally good and is sealed all the way.
The journey is described in stages from Kota Kinabalu to Bandar Seri Begawan. If you are traveling the other direction, just take the stages in reverse:
Kota Kinabalu to Beaufort (92km): The drive out of Kota Kinabalu is quite straight forward and well signposted. Road conditions are good and the road heading south from the city is a dual carriageway until just before Papar 38km away. From Papar, the road reverts to being a two-lane road, passing quiet coastal towns like Kimanis and Bongawan, where it leaves the coast to head to Beaufort. You can leave or join this itinerary at Beaufort (see the Get in section above for details), where you can head to (or come from) Menumbok (for/from Labuanor Brunei Car ferry), Kuala Penyu (for/from the Pulau Tiga National Park), or catch the train to/from Tenom.
Beaufort to Lawas (110km): The longest leg in the journey, it also used to be the most difficult as there were long stretches of the road which were not paved. This has since changed and although not the best, a continuous ribbon of bitumen now links Beaufort to Lawas. From Beaufort, go onto the metal bridge (turn right if coming directly from KK) across the Padas River and proceed to Sipitang 58km away. This stretch used to be unpaved but the road surface now is OK. You will pass the turn-off to Weston, a small seaside village which used to be the terminus of the North Borneo Railway. Sipitang, which clings along the beach, has quite a number of shops where you can break for a meal. The road swings inland heading to the Sabah-Sarawak border at Sindumin 18km away. The Immigration posts for are contained in one building on the border. As you leave Sabah, your passport will be stamped and your immigration card retained. A few meters on, at the other end of the booth, submit your passport to Sarawak Immigration with a new immigration card to be stamped into Sarawak. (Going in the other direction you hand your passport and card into the Sarawak authorities who will retun both to you and then you hand them into the Sabah authorities who will also stamp them and then return them.) This procedure may not apply to Sabah and Sarawak residents but check just in case. The one-street town of Merapok lies just ahead. A good road flanked by oil palm plantations goes the 35km. to Lawas. Just before reaching town, you will go onto a cable-stayed bridge across the Batang Lawas (Lawas River). You will also pass the junction to the Lunbawang village of Long Tuma and Lawas airport. See Lawas page for more info on the town. Lawas is also a point where you can leave this itinerary (see Get in above) by heading to Bakelalan in the Kelabit Highlands.
Lawas to Bangar (48km): This stretch used to involve a ferry and border crossing, but immigration checkpoints and a new bridge have eliminated them. From Lawas, take the road out towards Trusan, about 20 km. away. This will take you to the immigration point at Mengkolap on the Malaysia side 23 kms away. Once through that, it's another 100 meters to the Brunei customs at Labu. From Labu, its about 23 km. easy driving to Bangar, Temburong's administrative center.
Bangar to Limbang (20 km.): This leg of the journey is short and should be relatively easy as traffic is light. It involves crossing two immigration checkpoints and one ferry ride at the border. From Bangar, head west and after about 5 km., you will come to Kampung Puni where you go through Brunei immigration (opening hours 6am to 10pm). This is not a drive-through facility and the immigration post is a one-story wooden building on the south-side of the road. Park and get your passport and car permits done. Then proceed another 600 m. to the ferry landing point at the Pandaruan River, the border between Brunei and Malaysia. The ferry (RM8 or B$4) runs regularly and the crossing is almost ridiculously short. After landing on the Malaysian side, proceed to Malaysia's Pandaruan immigration checkpoint (opening hours 6am to 10pm) a short distance away. This is a drive-through facility although sorting out permits for cars may require you to park and get out of your car. With the opening of this checkpoint in June 2007, you no longer have the strange situation of having to get your Malaysian entry stamp (or exit stamp if traveling the other direction) in Limbang town. From Pandaruan, it is a simple drive to Limbang just under 15 km. away. You will pass Limbang airport just before entering town from the northeast direction.
Limbang to Bandar Seri Begawan: To head towards the Brunei border at Tedungan, 43 km. away from Limbang, you should head southwards out of town past the museum. The road, which is also the road to Nanga Medamit (the start of the Headhunter's Trail) runs parallel to the Limbang River. Take a right turn at the KM10 point (follow Nanga Medamit and Batu Danau direction) and travel for another 13 km. before taking another right turn. Going straight will bring you to Nanga Medamit. The road crosses the Limbang River at Batu Danau village and continues right up to the border checkpoint at Tedungan. Just before the checkpoint, there is a collection of shops and food outlets. They basically serve to quench the thirst of beer-starved people coming across from Brunei. Lines at the checkpoint can be phenomenally long, especially during weekends. Once you sort out Malaysian immigration and cross the border, you will immediately come to Brunei's Kuala Lurah checkpoint. Both Malaysian and Bruneian checkpoints have drive through lanes for you stamp your passport but you may have to get out of your car to sort out the necessary car permits. From Kuala Lurah, its about 15 km. to Bandar Seri Begawan and very good roads. There are several junctions and roundabouts but there are very good signposts.
This is one of the more comfortable ways of making the journey as you do not need to spend so many hours on the "road". The sea is also relatively smoother than traveling on the back roads of Sabah, Sarawak and Brunei (though on some days you may be in for a pretty rough ride). Note that the ferries are not wheelchair-friendly. A person in a wheelchair can make the trip (seated in an airplane-like seat for the duration of the ride), but be advised that some very capable help will be needed as it involves a good deal of lifting, carrying and balancing.
Though there are several ferries taking the route between Kota Kinabalu and Labuan and Labuan to Brunei, if you take the wrong ones you may end up being stuck and forced to stay overnight in Labuan.
To get from KK to Brunei in the same day, the following is a good strategy:
Get to the Point Jesselton Ferry Terminal in Kota Kinabalu at around 7:00am; earlier if a weekend. The terminal is a 20-minute walk from the center of town. At the terminal you can buy a "package" of two ferry trips (KK-Labuan and Labuan-Brunei) for RM56 (including the RM3 departure tax). You can also buy this package in advance, which is advisable for weekends and holidays, but you need to have your passport with you when you do so.
The ferry to Labuan leaves KK at 8:00am and arrives in Labuan at 11:15am. Once in Labuan, you have the option to take the 12Noon trip or the 1:30 pm trip in which you'll have some time for lunch (and cheap beer!), shopping and perhaps a quick visit to the Labuan Museum, or maybe a cab ride to and from the Labuan War Cemetery.
The ferry to Brunei leaves at 12:00 Noon and 1:30pm;. You need to pay a departure tax of RM10 at the ticket office. The ferry journey takes between one and one-and-a-half hours.
Once in Brunei, you'll go through immigration and customs at the Serasa Ferry Terminal. You can change money at the terminal. Then you board a shuttle to Bandar Seri Begawan. The shuttle costs B$2 and takes about 40 minutes to arrive at the bus terminal in BSB, in the southeast corner of the city. You will arrive in BSB sometime around 2:30pm if you take the 12:00 noon trip or 4:00pm if you take the 1:30 trip.
From Bandar Seri Begawan to Kota Kinabalu, the following is the best game plan:
Take the earliest express bus to the Serasa Ferry Terminal: it leaves at 6:40am from the last bay in the bus terminal in Bandar Seri Begawan, which is next to the bay for Bus #39. It costs B$2, and the trip takes about 40 minutes, getting you to the ferry terminal in time to buy a ticket for the 8:30am ferry departure to Labuan. Some schedules still show a 9:00am ferry as well but that does not go anymore; however, the 8:30am ferry usually waits until 9:00 to get as many passengers as possible.
The ferry to Labuan costs B$15. Unlike the KK-Brunei direction, there is no two-ferry "package," nor can you book tickets in advance. You can change your remaining Brunei dollars to Malaysian Ringgit, but remember to save B$1 to pay the departure tax. The ferry ride takes between one and one-and-a-half hours.
When you arrive in Labuan, you will go through immigration and customs; immediately afterward, go to the ticketing office and buy a ticket for the 1:00pm ferry, which seems to be the last ferry of the day to Kota Kinabalu. This costs RM34 for lower deck, RM39 for upper deck. Now you have a few hours to explore Labuan and have lunch. (Note: There is a left-luggage facility. The cost is 1-3RM depending on size however there is no tourist information desk in the ferry terminal.)
Warning: The ferry schedule is very much fluctuating and departures are cancelled quite often. For example on Sun 30 Aug 2009 there was no boat leaving Labuan before 3:30pm and the only way to get to KK to catch an AirAsia flight in time was to take a speedboat to Menumbok (RM15, less than half an hour) and a minivan-taxi all the way to KK (RM30 per person, leaves when there are 7 passengers in the car and the trip takes two hours).
The 1:00pm ferry arrives at the Point Jesselton Ferry Terminal in Kota Kinabalu at around 4:15pm. The terminal is an easy 20-minute walk from the center of town.
The direct ferry service between Serasa port (Brunei side) and Menumbok (Sabah end) taking up to 40 cars and 200 passengers each trip no longer runs. As at Jan 2012 it now goes to Labuan.
You will also find that there are many variations to travel between the two cities, especially at the Brunei end of the journey. The main route described here will allow you to make the journey in a day, while the variations may cause a delay in reaching your final destination.
Kota Kinabalu-Lawas-Bangar-Bandar Seri Begawan:
Three posibilities available - 1 Boring get on Bus in KK - get off in Bandar, Bus leaves daily from KK bus terminal.
2 Bus to Munumbuk - car ferry to Muara (http://www.pkljaya.com/Fares_Tickets.htm) - public bus to Bandar.
3 KK to Lawas then Bandar ( same route as 1 but using a variety of transport)
This is the fastest way in which you will be able to travel from Kota Kinabalu to Bandar Seri Begawan and you should be able to make it in a day. If you are going the other direction, do the stages in reverse. Here is the stage-by-stage description:
Kota Kinabalu to Lawas: Catch an early bus or minivans from Kota Kinabalu either directly to Lawas or by breaking your journey in Papar, Beaufort and Sipitang. Sipitang Express Bus Sdn Bhd has a 07:30 am express bus from KK to Lawas (RM20), taking about four and a half hours, allowing you to reach Lawas at about 12:00. The Lawas Bus Company express bus only departs KK in the afternoon and you will not make it to Brunei within a day. There are no direct minivans from KK to Lawas; you will have to at least change at Beaufort. If you cannot get direct minivans, you can change at Papar between KK and Beaufort, and at Sipitang between Beaufort and Lawas. Express buses leave from the Kota Kinabalu express bus terminal on Jalan Padang near the City Padang (City Field) in the city center whereas minivans leave from the open plot of land opposite Wawasan Plaza at the southern end of town. Minivans are most frequent early in the morning.
Lawas to Bangar: You will probably have to do this leg by taxis -- one from Lawas to the Brunei border at Labu and one from Labu after you pass Brunei immigration to Bangar. Don't forget to get the taxi driver to stop at the Mengkalap Immigration checkpoint at Trusan (about 20km from Lawas) just before the ferry so that you can stamp yourself out of Malaysia. There is no immigration checkpoint at the border. All this will of course turn out to be quite expensive. There may be minivans running up to Trusan or the border although they are not frequent. You could also try taking one of the rickety Lawas Bus Company buses from Lawas to Trusan but that will be as near to the border as you will get, leaving you only with taxis to continue the rest of the way to the border. Once in Brunei territory, taxis are your only option.
Bangar-Bandar Seri Begawan: From Bangar, regular speed boats make the half hour journey to Bandar Seri Begawan. These boats leave from the jetty in town and bring you straight into Bandar Seri Begawan. An added benefit going directly from Bangar to BSB, instead of continuing to Limbang, is that it allows you to bypass going through two more sets of immigration checks.
Kota Kinabalu-Lawas-Bangar-Limbang-Bandar Seri Begawan: This alternative is pretty much the same as the main intinerary; the difference is only at the Brunei end of the journey.
After leaving Lawas by taxi, instead of stopping at Bangar, you should continue by taxi from Labu to western Temburong-Sarawak border at Puni. At Puni, cross the Pandaruan River by boat or ferry and get stamped into Malaysia at the Pandaruan immigration checkpoint which was opened in June 2007. From Pandaruan, you can catch a local bus or taxi to Limbang, about 15 km away.
Once at Limbang, head to the jetty and catch a speedboat to Bandar Seri Begawan, which should take about half an hour. These boats leave when full and they are more frequent in the morning. However, if you have come directly from Kota Kinabalu, you may just make it for the last boats at about 4:30 pm.
If you miss the boat connection, you can catch a bus or taxi to the land border crossing at Tedungan (bus destination "Batu Danau") 43 km away. After clearing Malaysian and Bruneian immigration (the checkpoint is called Bukit Lurah on the Brunei side), catch the purple minibuses to Bandar Seri Begawan. These buses (B$1) operate til about 7 pm and the journey is about half hour.
Kota Kinabalu-Lawas-Bandar Seri Begawan: There is a daily Lawas-Bandar Seri Begawan ferry but they leave very early in the day. If you are coming directly from Kota Kinabalu, you will have to stay the night in Lawas if you want to catch the ferry. The only reason why you may consider this option is to avoid the expensive taxi ride from Lawas to Bangar in Brunei's Temburong district. Indeed, with cheaper accommodation options in Lawas, you may end up spending less by spending the night in Lawas. Also, you will only deal with one set of immigration checks - once by the Malaysians when leaving Lawas and then by the Bruneians when arriving in Bandar Seri Begawan.
Kota Kinabalu-Lawas-Limbang-Bandar Seri Begawan: There is a daily ferry between Lawas and Limbang but again, they leave early in the day, requiring an overnight stay at Lawas. Once in Limbang, there is plenty of time for you to catch the direct speedboat, or do the road trip, to Bandar Seri Begawan. This option allows you to skip the expensive taxi rides between Lawas and Bangar while still get to see the geographically unique outpost of Limbang. Again, you will only need to go through one set of immigration checks - either at Limbang Wharf and Bandar Seri Begawan jetty if you take the speedboat, or at Tedungan-Bukit Lurah if you go overland.
The usual next stop from Bandar Seri Begawan is Miri in northern Sarawak, which can be reached by road and bus. See Brunei's Get In section for details.
If you are heading to Kota Kinabalu, then it is highly likely that you'll be setting your eyes on Mount Kinabalu. See Kota Kinabalu's Get In section for details. However, before you proceed along the trail towards the mountain, you could make a detour to the northern part of Sabah. Kota Belud has an interesting tamu (market) and Kudat bills itself being at the northern-most tip of Borneo.
This is a usable itinerary. It explains how to get there and touches on all the major points along the way. An adventurous person could use this article, but please plunge forward and help it grow!