In the southwest part of the Faron Wetlands, you find half of Heart Lake, but the other has been swallowed by a rift.

Find Tri's Friends, Part 1

Go north and you can hold ZL to target the Deku Baba, then carefully pull it until it's defeated, and learn the Deku Baba Lv. 2 echo.

Defeat the Baby Gohma, then use a flammable echo like an Ignizol to burn the grass. This will also burn the spiderweb, so you can use echoes to go up and check on the glowing object to save one of Tri's friends.

Find Tri's Friends, Part 2

Go to the top of the wall, use echoes to get on top of the tree stump, and jump to the ledge to the east. Use another fire echo to burn the grass and the spiderweb, and check on the glowing object that was beneath it to save another of Tri's friends.

Find Tri's Friends, Part 3

Go to the south edge of this island and climb down the rock wall. When you're next to the spiderweb, make a flammable echo next to where you are on the rock wall, and when the spiderweb is gone, check on the glowing object to rescue another of Tri's friends.

Find Tri's Friends, Part 4

Climb up and to the west, and make your way to the west side of the sideways island where you burned the grass. Use echoes to reach the island west of that. Get in the water and go in the middle, where there is a deeper part. Press A to dive underwater.

Go to the left and create a Bombfish, press R to activate it, then use bind to move it into the water that is flowing downward. If you position the bomb correctly, it will break the broken block. Go to the top of the flowing water and let it take you to the small tunnel, where you can rescue one of Tri's friends.

Find Tri's Friends, Part 5

Swim down in the flowing water, then swim in front of the bubbles, then swim east and hold ZL to target the Deku Baba, then swim away from it to pull it off of the stem. Then use the bubbles if needed, then go to the right and check on the last of Tri's friends.

There will be a cutscene. Tri's level gauge will increase. You receive 2 Might Crystals.

There will be a cutscene, and your next destination is to find Blossu, who lives in a house in a corner of the wetlands.

Find Blossu

Go east and you can defeat a fish and learn the Piranha echo.

North of the Piranhas, you can defeat the large flower and learn the Giant Goponga Flower echo.

There is a cave southeast of the Giant Goponga Flower where you can learn the Beakon echo.

Go north in the cave until you reach a room with a maze. In the eastern half of the room, you can go through the northeast door and light all the torches to make a chest appear. Open it to get 50 rupees.

Go south again, and in the eastern half of the cave, there is a Piece of Heart that you can use echoes to reach.

Go through the southeast exit of the cave, then go east and you can defeat the Wizzrobe and learn the Electric Wizzrobe echo

Go east from there and check on the waypoint, then approach the scrubs and there will be a cutscene.

Afterward, go east and check on the glowing spot, then check on the entrance to go into Stilled Blossu's House.