Here's the link to the Vietnam Mountain Marathon site, as found by Pee Wee who reckons it's the perfect run for hashers. It takes place September 24-25 in Sapa, in the mountains 380km NW of Hanoi. It's easy enough to get to Hanoi via Don Meuang on Air Asia, but you'll then need to take either an overnight train or a death-defying bus ride.
Distances offered are 10km, 21km, 42km, 70km and 100km. If you're tempted by the 100km ultra marathon, keep in mind that it includes 4,300 meters of ascent. The shorter runs aren't quite so bad. In fact the 10km run looks no harder than some hashes we've done, with about 500m of ascent (though unfortunately all in the latter two-thirds of the run). Click on these to see them big.
Winning time for the half marathon was 2:06. There were nine men in the over-60 category and the fastest came in at 3:26 and the slowest at 5:42. Well, actually the 9th guy didn't finish and it's hard to blame him.
See the site for all the details, including complete transport/accommodation packages.