This week (Week 9 Season 4) you must find seven chests in “Fortnite Battle Royale“. Below you will find a video with all the sites of the chests in Moisty Mire.
Remember, then finish the game normally (or get killed) to properly save the challenge. If you leave the game manually without dying, it may not update the challenge. You can see everything under the Battle Pass challenges in the lobby. To play the challenges you need a Battle Pass for 1000 V-Bucks to unlock weekly challenges!