Does anyone here know if there is there any decent caving in north Vietnam? Work is sending me to Hanoi for a week and a half later this year and I'd like to try to get underground for a few days while I'm there. (I've seen the famous Phong Nha-Kẻ Bàng National Park, but that is in central Vietnam about 470km away.)
Thanks for any info or links!
Ari