The Bohorok river, which runs through Bukit Lawang, is a popular venue for tubing. Tubing is floatin  down the river in an inflated truck inner tube. You can hire tubes at many points along the river in the village for the day, walk up stream, and then float down the river as far as the Sibayak guesthouse. If you’d like a bit more of an adventure then you can try tubing to Bohorok, 10 kilometres downstream.