challenger

mountain climber

a mountain (large mass of earth and rock) or (large) hill / a mine (excavation usually consisting of small tunnels) / a heap, pile / the top or high part of an object / a chance, gamble / a climax, peak

person

(geography) steep

(geography) steepness

big, large, great

slope, gradient, incline, slant face, bevel / inclined plane

to challenge / (figuratively) to take on the challenge of doing something (especially something one has not done before); to try; to try one's hand at

challenge (against authority or a higher-ranked person) / (figuratively) try at something