Shots from M16s and AK47s crackle through the eucalyptus trees near Cu Chi, 40 km north-west of Ho Chi Min City, the former Saigon. People tiptoe gingerly through a clearing marked "minefield".
In a "command bunker" at the end of a dark tunnel several metres below the forest floor, a Viet Cong guerrilla called Le Van Tung offers me tea and khoai-mi, the white cassava roots (quite tasty when dipped in salt), which formed the staple diet of Vietnamese fighters.
It is all part of the war experience which the communist government is promoting here as a way of both remembering and cashing in on the valiant deeds of the winning side during the Vietnam War, which ended 25 years ago this Sunday. There are no real mines in the forest, and the gunfire comes from tourists firing off weapons at a dollar a bullet.
The tunnels themselves (entrance fee $4), with their long twisting passage-ways and chambers where mannequins pose in black pyjamas, are not genuine but a reconstruction for the benefit of naive visitors - who are told they have been widened from the original to accommodate fat US tourists. Mr Tung was genuine - at least he said he was - and he had a nasty bullet wound in his right shoulder to prove he saw combat.
The real thing, a fantastic multi-level network of 250 km of tunnels which at the height of the war provided munitions dumps, hospitals, dormitories and kitchens in an area stretching from Saigon to the Cambodian border, is some distance away and is mostly inaccessible to the public.
The tunnel system was begun during the war of the Viet Minh against the French, then extended and deepened as the Americans came to assist the South Vietnam army against the communists, and blasted the area around Cu Chi with overwhelming firepower, making it one of the most devastated areas in the history of warfare.
US troops tried everything to flush out the Viet Cong. Specially trained Alsatians were sent down, but "we used American soap to fool the dogs", said Mr Tung, who claimed to have killed US combatants himself, though he was reluctant to say how many.
Soldiers known as "tunnel rats" ventured in, only to fall into spiked traps of varying ingenuity with names like "swinging ball", "punching jump", "armpit stab", "double door-leaf" and "stickshot". Carpet-bombing and defoliation of the forests failed to dislodge the Viet Cong, who nevertheless paid a terrible price, losing 10,000 of 16,000 cadres.
A grainy video at a theme centre among the trees shows US planes bombing villages in what became known as the "Iron Triangle", and a commentator praises "American killer heroes" who fought the enemy "with a rifle in one hand and a plough in the other".
There are shops selling fake Zippo lighters - one with the inscription "Lover by night, fighter by day, killer by choice, Marine by mistake". And in an attempt to expand the site into an amusement park, a few bears, peacocks and monkeys and a caged python have been added to the attractions.
Most of the visitors are Vietnamese, for whom it is a moving experience. The names of 44,357 communist Vietnamese soldiers who died in the area are inscribed on the wall of a secular temple which has a computer database. No mention is made of the South Vietnam army soldiers, who have been written out of this weekend's commemorations.
Among the war tourists these days are US veterans. "Sometimes they cry," said Mr Tung. "Some say they hate war."