What happens is this: starting under water, tens to thousands of glowing red lights are seen rising out from the bottom of the river, then lifting hundreds of feet into the sky before disappearing.
The number one theory suggests that fermented sediment in the river, things such as decomposing remains and animal waste, release bubbles of self-immolating gas that rise to the surface and combust. That’s right, the best explanation science has come up with for the Naga fireballs is essentially that it eats too much meat. Suspiciously absent from this theory is a reason why the phenomenon occurs around the same time every year. Unless the Mekong eats a regimented diet of Activia yogurt, those meat eaters among us have to be somewhat suspicious of such a regular rate of expulsion.