This challenge is part of Fortnite Season 4 Week 9 Challenges and you'll have to pick up the five blue floating rings above Steamy Stacks. A very similar challenge had appeared before, but this time the rings changed place. They're no longer above the chimneys of the power plant, but all around the buildings.
Map
This time the bluish rings are almost all located on the machines of the place, or on the large metal pipes.
On the small extension of the westernmost building
On the pylon with the orange stripes
On the long central pipeline
In the crane, in the central hangar
On the ceiling, in the building to the northeast of the site
Steamy Stacks will be particularly contested during the week following the release of the challenge. However, the blue rings aren't consumed after a player collects them. This means that you can quite easily go to the place later in the game, when the fights are less fierce.
Original content by Romain "Zorg" Becquelin.