Son Doong cave is the biggest cave in the world. Discovering Son Doong is the most thrilling adventure tour in the world. This tour is limited tourists and in 2015, there were 500 people could book this tour. If you want to see Son Doong Cave in later this year is impossible because the tour closed from Sep to Jan due to the flooding season during this time. Therefore, you should book the tour from Sep to Jan and if you success to register with US$3,000 for price, you have to pass the health test before starting this adventurous and thrilling tour.