From Can Tho to Phnom Penh :

1. Direct bus from Can Tho bus station at No. 38C Nguyen Van Linh street, leaves once a day at 5:30 am. Ticket costs 340000 VND (or 16USD)/person and takes around 7 hours. Phone : (+84) 07103 761232

2. Alternatively, take a bus from Can Tho to Chau Doc, takes around 3 hours. Phuong Trang (futa) bus company is highly recommended. Phone: (+84) 7103769768
Then take a speed boat from Chau Doc to Phnom Penh daily departure at 8:00 am. Mobile: (+84)942234409

The first choice will be shorter and cheaper but if you want to stop by Chau Doc and enjoy the feeling on water way, go with the second one.

Go to Phnom Penh from Can Tho, Bac Lieu, Soc Trang

Currently, visitors can go everyday of the week with route Bac Lieu, Soc Trang and Can Tho - Phnom Penh and vice versa through two borders Tinh Bien ( An Giang ) and Moc Bai ( Tay Ninh ) . 

Contact to buy tickets : 
In Can Tho: 107 Tran Hung Dao/12 Nguyen Trai (at Petrol station No.99 ) Ninh Kieu District - Can ThoTel : 0710.3832 203 - 232 0710.3761 

In Soc Trang: Trà Men Bus Station - Tel : 200 079.3625 

In Bac Lieu: Bac Lieu Bus Station - Tel : 0781.3601 122Hoa Binh Station - Tel : 0781.3601144 

In Phnom Penh: 9D 230 Phasar Deumkor , Kokr Toul , Phnom Penh. Tel : (00 855) 997.609.88-099 790 443 

*Note: For Khmer passport shall be issued free of charge , while the peoples of the region through the border gate with a passport , foreign travelers will need a passport and visa . 

Go to Phnom Penh from Chau Doc. Ships, speedboats Chau Doc - Phnom Penh. 
You can go to Phnom Penh from Vietnam by water . The waterway is now popular Chau Doc - Phnom Penh.  

Quay in Phnom Penh: Number of 103 Sisowath , Phnom SK , Kh Daun Penh , Phnom Penh

Some carriers run Chau Doc - Phnom Penh and vice versa. 

Hàng Châu Express 
In Chau Doc : Con Tien floating restaurant , Tran Hung Dao Street , Chau Doc , An Giang. Phone : (+84) 076.3562771 
In Phnom Penh : No. 103 , Sisowath , Phnom SK , Kh Daun Penh , Phnom PenhPhone : +85-512932346

Self Travel Tips

Cách đi tới Shihanouk Ville (Cambodia) từ Hà Tiên.

Sihanoukville (Khmer: ក្រុងព្រះសីហនុ - Krong Preah Sihanouk), also known as Kampong Saom, is a province (khaet) of Cambodia on the Gulf of Thailand. Sihanoukville's beaches are a popular tourist destination in Cambodia.

 

Sihanoukville Ville - Self Travel Tips

Tips:

If you want to travel to Sihanoukville Ville by bus from Vietnam, usually take any local bus to Ha Tien Bus Station (Vietamese: Bến xe Hà Tiên), in Hochiminh City (Sài Gòn) it is recommended to take the Kumho Samco Bus Lines (more details here http://kumhosamco.com.vn/en/ho-chi-minh-ha-tien ). At the Ha Tien Bus Station, there'll be a minivan to transfer to Xa Xia (Ha Tien) - Prek Chak (Cambodia) border post.

If you arrive early to the border, there'll be more chances to catch buses. In 2010, Virak Buntham Express started a bus service from Ha Tien in Vietnam to Sihanoukville. Ticket price normally is 10 USD. Most of buses are in bad condition, stop several times to get passengers along the way and it may takes more than 4 hours to get to Sihanouk Ville.

In Sihanouk Ville, if the bus drops you at the bus station which closes to the local market, take a serviced -motobike to the beach (2 kilometers away) for 1 dollar (or 4000 Riel), bargain if they tell the price too high.

Suggested places to stay:

Apple Guest House, (100 metres off Serendipity/Ochheuteal beach.), ☎ +855 97 857 3786. Ochheuteal Beach. 15 clean rooms, close to the center. 2 minutes from the beach, private garden, rooms have cable TV & free Wi-Fi. Motorbike rental, laundry, internet, international calls and a very useful 24/7 convenience store. From $8-$15.

If you travel to Sihanoukville Ville on holidays in Cambodia, the prices may go up a little, a cheapest hostel will ask 10 USD for a very basic room. Go back to the local market to look for cheaper available rooms.

I accidentally visited Sihanoukville Ville on holidays and luckily found a guest house called 'Pheng Heng' near the market for 7 USD/fan room, the room was beautiful and you can go to visit the market in the morning because it is just on the opposite side. Tel: 0346584333 / 016 840 818/ 010 840 818.