Whether they're seeking pleasure or meaning, more and more vacationers are experimenting with dangerous drugs from foreign cultures.

Mountain ridge outside Doi Phu Kha National Park. Credit: Wikimedia Commons

On a hot, dry-season afternoon, David, then 25, found himself unable to speak, his vision blurring as the ground beneath him transformed into a pile of slithering snakes and snails. His pulse quickened and sweat pearled on his forehead; he quick-stepped to avoid the reptiles he felt brushing against his heels. He could hear his friends calling him but their voices were distorted, slow then quick, louder, then lost in the distance. A man came into focus before him. "Where is the bridge?" David asked, hoping to walk back to his hotel.

"It's right next to you," the man replied. David turned. There was no bridge. Turning back, there was no man. David was experiencing his first trip on magic mushrooms, consumed along the shores of the Nam Xong River in Vang Vieng, Laos.

After a day of beach hopping and beer guzzling with travel mates, E., then 19, entered his kayak to paddle back to his hostel along the marine blue waters of the Gulf of Thailand. Dehydrated, drunk, and delusional, he informed his friends he was tired and going to swim back....