A seasoned Vietnamese trekker/mountaineer shared with Tuoi Tre (Youth) newspaper his riveting experience during his expedition to Son Doong Cave, the world’s largest, and urged thrill seekers to make it to the cavernous wonder at least once in their lifetime. Nguyen Tam narrated his intriguing experiences during his thrilling five-day expedition to Son Doong, which is secluded in the core area of UNESCO-recognized Phong Nha-Ke Bang National Park in the central province of Quang Binh. Keen on preserving Son Doong’s pristine beauty and its environs, a local travel company which offers adventure expeditions to the cave makes it a point that only 10 tourists are allowed during each tour. A team of 25 members, including guides, kitchen staffers, forest rangers and porters were deployed to cater to the 10 tourists during his tour, Tam said. The Son Doong expedition is very physically taxing, as Tam and the other trekkers were pushed to their breaking point with such strenuous activities as wading across streams, canyoneering, mounting treacherous, slippery slopes and trekking through rough, vast terrain. A group of three members were tasked with helping female trekkers with certain daunting tasks. To reach Son Doong Cave, the trekkers had to hike through two densely forested expanses which span from Truong Son Tay Road to En (Swallow) Cave, and from En Cave to Son Doong Cave. En Cave is around two kilometers from Son Doong. The forests are infested with “vat” (terrestrial leech), which can stealthily sneak into holes on the trekkers’ clothing and suck their hosts’ blood until their bodies bulge. Some women screamed at the top of their lungs at the sight of the blood-sucking worms on their body parts as if they faced a predatory animal, Tam said. From the entrance of Son Doong Cave, the trekkers had to rappel to a depth of 80 meters. Armed with flashlights attached to their foreheads, they groped their way with great caution inside the pitch-black chambers. The trekkers often had to move on both their hands and feet and even buttocks to get themselves through precarious areas, Tam recounted. There were times when they had to put their backpacks on their heads while wading through deep waters. They were soaking wet, but it took a long time for their clothes to dry out due to the high humidity. “Our major concern was not about ourselves but our cameras, as we all wished to come home with as many photos of Son Doong as possible,” he added. Tam advised that potential Son Dong expeditioners pack their camera kits light, as cameras with lenses capable of taking wide and super wide angles will suffice. His other tip is to bring along a backup battery and a sturdy camera tripod. Taking gorgeous photos is also a challenge for visitors, Tam added. “There was no rush on this tour, with plenty of time for tourists to take photos and take in the splendor of the cave. However, photographers needed to seek the best spots in order to snap nice photos,” Tam divulged.  They also needed pools of light from the guides’ flashlights in pitch-black chambers. The high humidity also smeared the camera lenses. Tam noted that trekkers were supposed to adhere strictly to the tour organizer’s stringent rules regarding how to dispose of garbage and “answer the call of nature.” They were allowed to urinate anywhere in the forests or springs as their hearts desire, but were required to defecate at the camping sites into cans of rice husk, which would be carried out of the cave by porters for disposal.      “What expedition makers brought out of the cave were their delights and left inside it were their footprints only,” he said smilingly. Tam added that his trip companions from the UK, Spain, Israel, Denmark and the U.S. found the Son Doong tour, which costs around US$3,000, excluding airfares, good value for the money for all the rewards it brought and the organizer’s good services. Doctors were always on standby outside the cave and would show up within the day if need be, and the guides always had first aid kits and satellite phones on them, Tam observed. Prior to his Son Doong expedition, he had successfully conquered Mount Everest, the world’s tallest mountain; Death Valley in the U.S.; and Mount Fansipan in northern Vietnam, which is dubbed the “roof of Indochina.” “It takes twice as much as stamina and physical strength to surmount Son Doong compared to Mount Fansipan. One of my tips was to prepare myself physically for the Son Doong expedition with regular workouts several months before the tour began,” he disclosed. “Despite the tour costs which many Vietnamese may find exorbitant, I strongly suggest you make a once-in-a-lifetime expedition to Son Doong Cave,” he urged. Following the live coverage of the American Broadcasting Company and the National Geographic Magazine’s 360-degree photo essay on Son Doong Cave earlier this month, local travel firms have reported a surge in the number of domestic tourists who have inquired about expedition tours to the cave. Nguyen Chau A, director of Oxalis Adventure Tours Co. which offers adventure excursions to Son Doong and En Caves, told Tuoi Tre that tours to Son Doong during 2015 have long been fully booked, with many applicants now on a waiting list. The company offers tours to the grotto from February to August each year, as the cavernous terrain turns precarious during the remaining months, which coincide with the rainy season. Oxalis’s Son Doong expeditions are available with weekly departures and are strictly limited to 10 guests, according to the company’s website. At the time of booking, tourists will be asked to complete a number of questions related to their fitness and medical history to make sure they are fit for the taxing trip. Eligible applicants are also supposed to have some previous outdoor experience such as trekking, or camping over rough terrain. Son Doong Cave is endowed with mammoth chambers that can comfortably house a 747 airplane or an entire New York City block full of 40-story buildings. The cave was first explored in 2009 by a British caving expert, Howard Limbert, and a local named Ho Khanh. The cavernous wonder has made headlines in other world-famous media outlets, apart from the American Broadcasting Company and National Geographic Magazine.