Thailand, Myanmar, and Laos, separated by rivers Ruak (Myanmar and Thailand) and Mekong River (Myanmar, Thailand, and Laos), meet at the famous Golden Triangle; where you can be in three places at once.
Tours are available for one to try navigating the Ruak and Mekong River or for a three-day cruise going up to China through Mekong. Smaller tugboats have a hard time going upstream so I'm pretty sure it's not advisable.
