The Giant Teak Tree in Nam Pat is said to be world's largest teak tree living today. That "largest" is measured at the perimeter and at 1.30 meter above ground the tree has a said perimeter of 9.85 meter (measured on 13 October 1982) and a height of 47 meter. It has estimated longevity at least 1,500 years old. Surrounding the Giant Teak tree, there are medium sized teaks, teak seedlings in the teak-dominated mixed deciduous.
The numbers do not really add up when you see the tree in reality. But never mind it is a very nice park (free entrance). In 1977 the height of the tree has been reduced to 37 meter due to a storm. Photo above is The tree in 1985 (left), in 2005 (middle) and in 2015 (right).
A long time ago it was easy to declare something the biggest, the longest, the whatever. But nowadays things are checked very easy. I did some research and this tree is never mentioned anywhere but a teak tree in Myanmar and India. Well of course it is mentioned by the TAT.