Don Sao Island
If you find yourself at the borders of Laos, Myanmar and Thailand (AKA The Golden Triangle), it is actually possible to take a short trip across the Mekong River to the Laos side, without the need for a Laos visa.
In the town of Sop Ruak (Thailand side), there are plenty of fast boats and pilots willing to take you over to Don Sao Island, where there is a small market, selling Laos clothing, handicrafts, postcards etc and if you want to send a letter home with a Laos postmark, there is even a small post office here.
The round trip will cost you four or five hundred Thai Baht and includes a quick dash up to the banks of Myanmar to look at the well known Golden Triangle Paradise Resort casino, before heading over to the Laos side.
When your boat drops you off (the boat will wait for you to take you back to the Thai side), you will pay a small 20 Baht tax to the official in a little booth, thereafter you can wonder around the small, low key market. If you fancy some Laos whisky with pickled snake and scorpion, this is the place to come.
Advertisement: Coming to the Laos? Take a look at our hotel rates: Laos Hotels

Honestly, you can't really say you've had the 'Laos experience' if you make this short visit to Don Sao Island. You cannot go further inland, all you see are some market stalls and the whole set up is a tourist trap. You don't even get a stamp in your passport... but it's a good photo opportunity, a good place to pick up some local souvenirs and indeed a good opportunity to take a ride on the mighty Mekong river.
Technically, it's Laos territory and you can say you've been to Laos. If you won't be having the opportunity to see more of Laos, it's worth the trip... but it's really nothing more than a tourist trap.
(Hint: Get the post master on the island to stamp your passport with the Laos postmark, to prove you've been there).
See also: Don Sao Island - Worth the trip?
Need advice? Got a question? Go to our Laos Forum

