Related Clues:
- They may be rubber
- Liquefied rocks
- Boats that inflate
- River awfully fast -- these may help
- Travels through a canyon, perhaps
- Travels through the Grand Canyon, say
- Balsa vessels
- Volcanology specimens
- Finn's vessels
- Castaways' constructions
- They may be inflatable
- Some flotation devices
- White-water rides
- Travels rapidly?
- Pool inflatables