Getting in Cambodia
All visitors, except citizens of Indonesia, Malaysia, Singapore, Philippines, Laos, Thailand and Vietnam need a visa to enter Cambodia,
The official price for a tourist visa is US$20, and US$25 for an "ordinary visa" also known more commonly as "business visa". Staff may try to charge more at some land border crossings: hold out for the official price, particularly at major crossings, but don't be upset if you have to pay US$1-2 extra. The major difference between a tourist and an ordinary/business visa is that a tourist visa can only be extended once, for maximum 2 months of stay in Cambodia, whereas an ordinary/business visa can be extended for extended periods up to a year and more.
Visas can be obtained at Cambodian embassies or consulates. Visas are also available "on arrival" at both international airports, all six international border crossings with Thailand, some international border crossings with Vietnam, and at the main border crossing with Laos.
At Phnom Penh airport head to the Visa on Arrival desk, join the queue to the left, where your application form is reviewed (you should have been given the form on the plane). Then move to the right and wait for your name to be called. You then pay and receive your passport with the visa. Officials have difficulties pronouncing Western names so stay alert and listen out for any of your names in your passport, any of your given names or surname may be called. Once reunited with your passport, join the Immigration queue.
In Poipet, several scams abound. A favourite is the Cambodian custom officers ask tourists to pay 1000 Baht (about US$30) for a visa on arrival, instead of US$20. This includes embassy in Canberra, Australia. Stand firm but stay friendly and keep smiling, they rarely insist it. Scams on the Thai side of the border, at Aranyaprathet, are even more common. Don't get on a 'government bus to the border', don't accept the help of someone who 'works for Thai Immigration' at your hotel or elsewhere, and don't go to shops marked 'visas available here' next to the border. If you don't have a passport photo immigration officers will scan in the one on your passport for $US1-2.
Citizens of most nations can apply for an e-Visa (web), online on the Ministry of Foreign Affairs and International Cooperation website, through a service provided by a private Cambodian company (CINet web). This is a normal Tourist Visa but costs US$25 instead of the normal US$20. The visa arrives as a PDF file by e-mail within 3 business days. The application requires a digital photograph of yourself (in .jpg format). You can scan your passport photo or have a passport sized photograph taken with a digital camera. There are other websites pretending to make a Cambodian e-visa - at best, these are just online travel agencies which will charge you more ($30-$45) and get the same $25 visa for you; at worst, you may end up with a fake e-visa.
You need to print two copies (one for entry and one for exit) of the PDF visa, cut out the visa parts and keep them with your passport.
Visas in advance (either online or from an embassy/consulate) save time at the border but are more expensive. However, you do get to skip the queues of people applying for the visas arrival, although sometimes you may simply spend the saved time waiting at the airport luggage belt for your suitcase.
E-Visas are only valid for entry by air or at the three border main land crossings only: Bavet (on the Ho Chi Minh City-Phnom Penh road); Koh Kong (near Trat in Eastern Thailand); and Poipet (on the Bangkok-Siem Reap road). You may exit the country with e-visa via any border crossing, however web. Given the general reduction in visa scams at the major land borders, paying the extra $5 to guarantee the price may (more likely if entering from Thailand) or may not worth it. Getting a tourist visa on arrival for US$20 is more likely than being overcharged. Plus it keeps the option open of the enjoyable Phnom Penh-Chau Doc boat trip (and the use of other minor border crossings)!
Updates: Cambodia e-Visa charges US$3 more effective 5 Feb 2013
Overstaying in Cambodia is dodgy. If you make it to Immigration and are less than 10 days over, you'll probably be allowed out with a fine of 50,000 riel per day. However, if for any reason you're caught overstaying by the police — and drug raids etc are fairly common — you'll be carted off to the notoriously unpleasant illegal immigrant holding pens and may be blacklisted from Cambodia entirely. For most people it's not worth the risk: get a legal extension or do a visa run to the nearest border instead.
Extending a Visa
While technically it is possible to extend your visa by going to the immigration authority next to Pochentong airport, it is highly recommended that you use the services of one of the numerous agents that offer this. The commission they charge is likely to be lower than the cost of taking a tuk tuk to immigration and back, and in addition you are likely to save many hours, since these agents have the process streamlined. Nearly all guest houses will handle the visa extension for you, and you will receive your passport back in a couple days.
Cambodia has international airports at Phnom Penh and Siem Reap.
Note, in the list of borders below, the Cambodian town comes second. E.g. Aranyaprathet is in Thailand; Poipet is in Cambodia
All six border crossings with Thailand are open 07:00 to 20:00, each offers Cambodian visas on arrival. All the crossings are served by paved roads in both countries, except the Cambodian side of the Daun Lem crossing, which is being paved as of March 2012.
Thai buses run to but not across each of the crossings: even Chong Sa-Ngam, the last to achieve Thai connections has now gained minibuses that bring gamblers to the new casino in Choam.
In Cambodia, four of the six border towns (Poipet, Koh Kong, Daun Lem and O'Smach) are directly served by buses. Pailin, Anlong Veng and Samraong (each less than 20 km from a border) are each served by buses; motorbikes and shared taxis connect each of the towns with their respective border crossings.
Cambodia's busiest land crossing is at Aranyaprathet/Poipet on the Bangkok - Siem Reap road in North-western Cambodia. Long the stuff of nightmares, the roads are now paved all the way from Poipet to Siem Reap, Battambang and Phnom Penh.
Coastal Cambodia and the southern part of the Cardamom and Elephant Mountains region is served by theHat Lek/Koh Kong border. The road goes all the way to Sihanoukville. From Trat in Thailand, there a minibuses to the border. In Cambodia, minibuses or taxis connect the border to Sihanoukville and Phnom Penh. The Koh Kong - Sihanoukville boat service no longer runs.
The former Khmer Rouge stronghold of Anlong Veng is close to the Chong Sa-Ngam (in Si Saket Province)/Choam border. Pol Pot was killed and burned within walking distance of immigration.
Improving roads in North-western Cambodia are making Samraong emerge as a transport hub. It is close to the Chong Jom (in Surin Province)/O'Smach border and well linked with Siem Reap.
Eastern Thailand is connected to Battambang and Siem Reap by the Ban Pakard (in Chanthaburi Province)/Phra Prom (near Pailin) crossing, which offers a less stressful and more scenic alternitive to the more northly major crossing at Poipet.
The geographically closest crossing to Battambang is that at Ban Leam (in Chanthaburi Province)/Daun Lem. Paramount Angkor run buses to Battambang though as of March 2012 the road on the Cambodian side is not yet fully paved.
Vietnamese visas must be obtained in advance from an embassy or consulate. This can be arranged easily in Cambodia.
The main crossing is the Moc Bai/Bavet crossing on the Ho Chi Minh City - Phnom Penh road. Buses between the two cities cost US8-12 and take around 6 hrs. Passengers vacate the vehicle at both countries' checkpoints. Only one passport photo is required for a Cambodian visa on arrival. Tours of the Mekong Delta (US$25-35, 2-3 days) can provide a more insightful journey between the two cities.
If you end up on a Kumho Samco bus even after being told the ticket is for another company it is possible to avoid the extra charge by being quick and getting through Vietnam border crossing and then going straight to the Cambodia side 100 meters away. The conductor will wait for all the foreign passports needing visas then jump on a motorcycle (if he is nice you can get a lift if he is leaving to go when you are). It is a gamble but doable as they will threaten to wait only 10 minutes. Ask for a visa on arrival sheet on the bus to have the paperwork ready. If you do miss the bus some buses at least stop less than a kilometer or so down the road for a half hour food stop. Best bet avoid Kumho Samco and the extortion.
Tickets to Siem Reap are also available (US$18), though it is cheaper to buy a ticket to Phnom Penhand then arrange onward transport on one of the many connecting buses.
Close to the coast is the Xa Xia/Prek Chak border. Cambodian visas are available on arrival. Buses run between Ha Tien in Vietnam to Sihanoukville and Phnom Penh in Cambodia.
Coastal areas are also served by the Tinh Bien/Phnom Den border near Chau Doc in Vietnam.
The Xa Mat/Trapeang Phlong crossing on the Ho Chi Minh City - Kampong Cham road is not well served by public transport but may be useful for accessing Kampong Cham and Eastern Cambodia.
Banlung in North Eastern Cambodia is served by a crossing at Le Tanh/O Yadaw near Pleiku in Vietnam. Visas are available on arrival, one photo required. Change buses at Le Tanh.
Stung Treng in Cambodia is connected to Pakse and the Four Thousand Islands region of Laos by the Voeung Kam/Dom Kralor border. Onward transportation is not regularly available. Cambodian and Lao visas available, but require a $1 to $2 fee on both sides of the border. Travel agencies on both sides offer border crossing packages.
To/from Laos - There is one border crossing for tourists on the Mekong, a 90 minute speedboat ride north of Stung Treng. The border guards have few opportunities for "alternative" income, and will usually try to make a few extra dollars from scamming tourists.
To/from Thailand - There are no ferry services between Cambodia and Thailand. The Sihanoukville - Koh Kong ferry no longer runs.
To/from Vietnam - It's possible to travel between Ho Chi Minh City and Phnom Penh by boat, or by combination of road and boat. Fast boats leave daily from Chau Doc in Vietnam's Mekong Delta and take 5 hours to reach Phnom Penh. Chau Doc is a four hour drive from Ho Chi Minh City. A popular overland route is to make a three day trip, stopping at Can Tho and Chau Doc before taking the boat to Phnom Penh.