What did Lewis and Clark use to travel?

Answer 1

They had:

1 Keeled boat light strong at least 60 feet in length her burthen equal to 8 tons

1 Large Wooden canoe

They also had horses, walked, climbed, and used pirogues. "Pirogues" is a French word meaning that they tied smaller canoes together to make a kind of raft.

Their horses were certainly used as pack animals in the rough country, and for riding when they crossed the flat plains.