inner-tubing

[in-er-too-bing, -tyoo-] /ˈɪn ərˈtu bɪŋ, -ˈtyu-/
noun
1.
tubing (def 4).
British Dictionary definitions for inner-tubing

inner-tubing

noun
1.
the sport of floating on rivers, rapids, etc using a large inflated inner tube as a buoyancy device