| paca | a rodent that lives mostly in Central and South America |
| rugged | having a rough and uneven surface |
| musher | the driver of a dogsled team |
| vowed | promised |
| checkpoint | a place along a route where a check or count is made |
| volunteer | someone who helps free of charge |
| blizzard | a long, heavy snowstorm with strong winds |
| whiteout | heavy clouds over snow leading to completely white conditions that make it impossible to see |
| refuge | a safe or covered place out of bad weather |
| burrowed | dug a hole like a small animal |
| experienced | having the knowledge or skill from having done a particular thing in the past |
| layover | a brief stop on a trip |
| squinted | looked with eyes partly open |
| courageous | having or showing courage, brave |
| remote | distant; far from towns or cities |
| momentum | the force and speed of a moving object |
| purebred | animals coming from many generations of the same breed or kind |
| trailhead | a place where a trail begins |
| jaguar | a large spotted wild cat that lives in parts of Central and South America |