I had a conversation about these critters last week. They are found, fortunately enough, in Queensland, Australia but not in Thailand. Their venom is neurotoxic and extremely dangerous. They commonly grow to a meter and a half in length.
If you come across one, run.
Snakebites are one of the leading causes of death in Myanmar, where I once briefly worked as a lawyer before being fired by a jealous, Spanish HR person who was upset because I wouldn’t ask the Spanish ambassador to renew her passport. I invited her to come along and meet the ambassador; she could ask him herself for the favor if she wanted to. I didn’t know the ambassador and felt that such a request would be presumptuous.
This was the only run-in I had with a snake in Myanmar.