We just completed the 5-day, 4-night Han Son Doong expedition with Oxalis and I can safely say it is like nothing I have ever done before. The trek to and through the cave is intensely physical and I can see why they say they've had to turn people away before - a word of advice...definitely follow their advice on how to train!
Having said that, we never felt rushed in the cave, and we never felt unsafe because the team are all consummate professionals - everyone from our main guides Thang and Adam, the assistant guides Bien, Hoay, Ling and Dang, and the staff in the head office were wonderful. Our main chef Bun kept us really well fed (I already miss my daily pho breakfast) and the team of porters ensured camp was always well set up by the time we reached at the end of the day.
This type of trip is not for the faint-hearted, but if you're willing to put yourself out of your comfort zone and want to see landscapes and formations that few will ever see, sign up...immediately!More