Most visitors carry on from Udon Thani due north to Nong Khai, but making a detour via LOEI, 147km to the west, takes you within range of several towering national parks and sets you up for a lazy tour along the Mekong River. The capital of a province renowned for the unusual shapes of its stark, craggy mountains, Loei is also the crossroads of one of Thailand’s least-tamed border regions, with all manner of illegal goods coming across from Laos. This trade may have been reined in – or perhaps spurred on – by the opening in 2008 of a 3km-long bridge across the Heuang River, 80km northwest of Loei, to Xainyabouli province in Laos (the crossing is open to foreigners, but there’s no public transport on either side). Despite its frontier feel, the town, lying along the west bank of the small Loei River, is friendly and offers legitimate products of its own, such as sweet tamarind paste and pork sausages, which are for sale along Thanon Charoenrat, Loei’s main street, and the adjacent Thanon Oua Aree. But Loei is really only useful as a transport hub and a base for the nearby national parks. The most popular are Phu Kradung National Park, which has some excellent walking trails, Nam Nao National Park, home to around a hundred different species of mammals, and Phu Reua National Park, which affords magnificent views over Laos.