The Hermit’s Cave of Treasure (Rue Si Simbat Cave)

Rue Si Simbat Cave near Lom Sak, Phetchabun, is a limestone cave with a genuine wartime story: in 1944, it was designated a vault for Thailand’s gold reserves and the Emerald Buddha, hidden here from Japanese forces during a scrapped plan to relocate the capital. Entry is free, and it’s about 36km from Phetchabun town.

The history is specific enough to be worth knowing before you go. Field Marshal Plaek Phibunsongkhram, then prime minister, issued an administrative order in 1944 establishing Phetchabun as an alternative capital in case Bangkok fell to Japanese occupation. As part of that plan, gold bars were transported from the Ministry of Finance in Bangkok and the Emerald Buddha itself was prepared for hiding inside the cave, safely away from Japanese soldiers stationed elsewhere in the country. Parliament ultimately rejected the capital-relocation scheme, and the treasures were shipped back to Bangkok before the war ended — the Emerald Buddha has sat in Wat Phra Kaew ever since. What’s left on site today is the memory of that episode rather than anything valuable: a naga-flanked staircase leads up to the cave entrance, a hermit statue stands inside giving the cave its name, and the crumbling remains of a gun emplacement built to guard the stockpile still sit outside the mouth of the cave.

Inside, it’s a working limestone cave rather than a lit tourist route — expect uneven, sometimes damp footing and no installed lighting beyond what daylight reaches near the entrance. Locals visit as much for the history and the hermit shrine as for the cave itself, and it sees far fewer visitors than Phetchabun’s better-known waterfalls and national parks. For the fuller wartime picture, the Lomsak Museum in town covers the region’s WWII-era history in more depth.

There’s no restaurant or shop at the site itself, so bring water if you’re planning to linger over the gun-emplacement ruins or read up on the history before heading back to Lom Sak. The turnoff from Highway 21 isn’t heavily signed, and mobile signal can be patchy in the approach — downloading directions or asking at a fuel station in Lom Sak before you set out saves backtracking on the final unmarked stretch.

Insider Tip: Bring your own flashlight — there’s no lighting inside beyond the entrance chamber, and the WWII gun-emplacement ruins outside are easy to miss if you don’t know to look for them.

Watch out: The site isn’t signposted from the main highway in the way a museum or temple would be — follow Highway 21 to the km 251-252 marker, then the side road for about 4km, and ask locally if the turn isn’t obvious.