Ban Houayxay, also known as Huay Xai, Houei Sai etc is the capital of the Lao province of Bokèo on the border with Thailand.
The town lies on the Mekong river opposite Chiang Khong in Thailand being the northernmost border crossing between the two countries. The two are only connected via ferries.
Houayxay has a domestic airport with regular flights to Vientiane (capital of Laos) and Luang Prabang (depending on the season). Probably the most popular means of transport are boats (speed and slow boats, freighters, luxury cruisers for tourists and others) running down the Mekong to Pakbeng, Luang Prabang and other destinations.
(http://en.wikipedia.org/wiki/Ban_Houayxay)