This challenge is part of Fortnite Chapter 2 Season 1 "Alter Ego" Mission. You have to conquer Mount Kay — which is the highest peak on the game's new map. You will find it in the small snowy biome to the southeast. It is easily spotted, even from the battle bus.
Map
To complete this challenge, you will need to wear the Journey outfit — which you can unlock at level 1 of the Battle Pass. Note that the challenge states that it is enough to summit the highest mountain, meaning that you can reach it from the air, via the battle bus, or climb it on foot if you feel like it!
