Difficulty: Any
Location: The Suburbs - Sewers
You'll find your way into the sewers with Henry and Sam and you'll enter a flooded area where Henry will turn a wheel to lift a gate open for you to swim under. You'll need to remove a piece of metal underwater that's keeping it shut too. Swim and navigate your way to the top of the next room where you'll find a pallet that you'll push into the water. You'll then push this pallet back into the previous room where Ellie will hop on. Bring her over where the control panel is and she'll hop off and begin the process of turning on the generator. This is where you'll immediately swim back to where you just got Ellie and hop out of the water to meet Henry and Sam as Ellie will turn the power on. Hop onto the platform that Henry and Sam are standing on and you'll ride that across the room to meet Ellie. The trophy will pop as soon as the ride is over.
For a visual guide, here is a video by PowerPyx. Start at 44:06