What are the risks associated with swimming in the Mekong River?

Question

I read (mirror) that people sometimes swim between Laos and Thailand across the Mekong River. Aside from immigration matters and possible strong streams, what are the risks (e.g., hostile piscifauna) associated with swimming in the Mekong River?

Answer 1

Some answers in the comment section: problems may arise from the presence of boats, water pollution, the ongoing political turbulence in Myanmar, giant stingrays (600kg) and crocodiles.

• Probably depends where, but I would think in many areas boats (potentially quite large) can be quite a danger. The quality of the water may also be less than ideal, if you're thinking about doing that for recreational purposes. – jcaron Apr 26 at 14:47
• If you are planning to do this at the golden triangle: you need to be a good swimmer: the river is quite wide there. There is also a risk of drifting into Myanmar which is definitely not a great spot to be at the moment. I'm also fairly sure it's forbidden to just jump in the water from any bank of the river by local immigration, but I have no data to back that up, – Hilmar Apr 26 at 15:11
• WWF says there are giant stingrays (600kg) and crocodiles, but they're endangered so probably not very likely to be encountered. – Nate Eldredge Apr 27 at 3:27