| A | B |
| obstacles | things that block progress |
| spectators | people who watch an event |
| pace | speed |
| mushers | drivers of teams of sled dogs |
| checkpoint | a place where vehicles are inspected |
| cargo | things carried by a ship or vehicle |
| handlers | people who touch, hold, or lift something |
| runner | one of the rails on which a sled slides over snow |
| tributary | a river that flows into a larger river |
| straggle | to move in a scattered group |