I did the tubing as a sole traveller. You meet people on the tuk tuk to the river and can chose to go down the river with them or go your own way. Scenery is breathtaking and it is fun meeting and talking with people in the three bars along the way. Some even have basketball and volleyball for you to play. Yes there are lots of travellers in the bars drinking wih little interest in the tubing - but you can either join in or ignore it and tube down the river having just a few drinks.