Vietnam Visa and entry regulations.
From Koh Kong, Cambodia you can visit the town of Ha Tien on the border of Vietnam and Cambodia. Which is a free visa entry valid for 4 weeks. Since 01 July 2015.
To get there you can catch a mini bus at the Koh Kong bus station, costing about $6-$8 taking you to Kampot.
From Kampot over Kep to Vietnam you Pay $10 for Taxi or Minibus where you continue to the Vietnam border. This company will bring you to Ha Tien Town.
The owner of the Oasis Bar in Ha Tien Vietnam, where the bus stops will be happy to give you more information.
Visit the Oasis Bar website here.
Address: Hà Tiên, Kiên Giang, Vietnam
Saturday – Sunday Closed.
New rules for Visa free access to Vietnam.
Since 01 July 2015, tourists from different countries can enter Vietnam for 30 days without a visa.
here it goes to the official Vietnam website for Visa and entry regulations
Cambodia Visa information.