Translation of "Harshest" in Japanese

I'm Bear Grylls, and I've survived in some of the harshest places on the planet.

俺はベア・グリルス 地球上で最も過酷な場所に 挑んできた

[shouting over airplane] Let's go and find this wreckage. [Bear] We're flying west over some of the harshest terrain in the world.

残がいを見つけるぞ 世界屈指の厳しい地形の上を 飛んでいる