You go northeast to reach Jabul Waters, where Tri saw a large rift.
Seesyde Village
The first location you reach in the Jabul Waters area is Seesyde Village. Approach the people east of the waypoint and there will be a cutscene.
Go east and check on the Stamp Stand.
Go to the south end of the pier to see a Might Crystal under the south end of the pier. Go underwater to get it.
Go into the water and swim southwest to find an old ship in the water. Near it, there is a shark-like monster. Switch to swordfighter mode or use echoes to defeat it, then learn the Chompfin echo.
If you go southeast in the water, you eventually find a chest surrounded by Sea Urchins. Use Swordfighter Form or an underwater monster echo to defeat them, then open the chest to get 20 rupees.
Keep going east and you find a chest that contains 5 pieces of bubble kelp.
Farther east, you find electrified jellyfish. Use swordfighter form or an underwater monster echo to defeat them, and learn the Biri echo.
East of them, there is a Stamp Stand in the water.
Back in the village, you can talk to the woman on the southwest part of the pier to start the quest Deliver the Grilled Fish.
If you go north of the village, then east, you can go across a bridge. From there, start by going south to find a beach. In the eastern part of the beach, approach the counter to find a Business Scrub. Talk to the business scrub to start the quest Out of Bubble Kelp.
If you go south from here, you can go into the cave on the island with the Zora woman on it, and dive down into the hole in the north part of the water, northeast of the Zora boy. Go down in the water (swim past bubbles to refill your dive meter) and swim in front of the chest, and open it to get 10 pieces of bubble kelp.
Go farther underwater (swim in front of glowing coral to light up the nearby area) to find Tangler Lv. 2s. Defeat them with swordfighter form or an underwater enemy and learn the Tangler Lv. 2 echo. Then swim to the end of the path and go up the ladder. Go south to exit the cave.
Go northwest from the smoothie shop to find a waypoint to add to your map.
Then go back to the smoothie shop and go up the ramp behind it. Defeat the jumping four-legged monsters and learn the Tektite echo. You can dive underwater to be safe from the Tektites, and use a flying monster echo such as a Peahat to defeat them.
When you can't go farther north, go northwest and check on the waypoint to add it to your map.
Go west across the bridge and there will be a cutscene. Go into the building to enter Lord Jabu-Jabu's Den.
Lord Jabu-Jabu's Den
Follow the path and go north until there is a cutscene. Then go south to exit the building.
First, warp to the waypoint to the south. Then go south, and you can optionally talk to the Zora in the water. South of that Zora, there is a chest buried in the sand underwater. You can dive down and press X to bind to the chest, then move away from the chest to pull it up. Open it to get 50 rupees.
Keep going south to reach the part of Zora Cove with a big fish tail sticking up out of it. Hop out of the water there, and check on the waypoint to add it to your map. Then go south to fall in the water, and dive underwater to go through the door in the side of the island.
Sea Zora Village
You can visit the Sea Zora Village shop in the southwest part of the cave.
Go north up the stairs and corals, and go through the door in the north wall. There will be a cutscene.
Teleport to the waypoint west of the Smoothie Shop, and go north to Crossflows Plaza. Speak to Kushara and there will be a cutscene.
Teleport to the waypoint to the north, near Jabu-Jabu's Den. Then go west. There is a Stamp Stand just to the west of the small rift.
Zora's River Cave
Then go north and look for a cave near the west side of the giant rift. Go inside. You can ignore what the sign says. Drop a boulder on the Bombfish or hit it some other way, then get away from it. After it explodes, learn the Bombfish echo. Go east and ignore the sign again, and drop a Bombfish on top of the Sea Urchins and the Tangler. Then go east. Use a Bombfish or other underwater monster echo to defeat any Tanglers in your way, then go onto the island with the ladder on it. Climb down.
Go down to the bottom, where there is a broken block. Create a Bombfish next to it, then press R to spin, then swim away from the flashing Bombfish. After it breaks the block, go west past where the block was.
Go upward, but try not to hit the Bombfish in the way. Then go west and create a Bombfish next to the block, then press R to spin and make the Bombfish flash, and swim away. When the Bombfish destroys the block, go west past where it was, and make sure to swim in front of the bubbles to refill your dive meter. Swim west to the next area.
You'll be locked in a room with five Bombfish. Create an underwater monster echo to hit the bombfish for you. As long as you stay near the right side, the Bombfish won't start flashing when it swims close to you. But keep an eye on your dive meter, and swim to the bubbles in the southwest corner as soon as you can, to prevent your dive meter from running out.
Afterward, go through the door that opened. Go upward, and if you want the chest on top of the piece of wood, you have to create echoes that let you go up high enough to create an Ignizol and pick it up so that its flame is touching the wood. Then bind to the chest and make it fall down through the hole. Stand in front of it and open it to get a golden egg.
Go up the ladder. Step on the button to open the door. Go through. You'll be back in the first room of the cave. Go south to go back outside.
Continue Exploring Zora's River
Go north from the cave, then when you see a bridge to the left, first go northeast toward the cave. Before you go in, defeat one of the dragonflies and learn the Needlefly echo.
Zora's River Cave 2
Jump onto the wooden box, then bind to the wooden box behind the bars to the north. When the wooden box is on top of the button, the door will open. Go through.
Jump onto the wooden box and bind to the northern box behind the bars. Whenever the box is stopped by a step, jump up. When the box is on the button, the door will open. Go through.
Bind to one of the boxes and drop it in the water, then bind the other box and set it on top of the first box. When the upper box is north of the bars on the left or right side, move the box toward the button until you can drop it on the button. When you do, a chest appears. Open the chest to get 100 rupees.
Leave the cave, and go to the bridge to the west. Go north on the bridge to reach the River Zora Village. Check on the waypoint to add it to your map.
River Zora Village
In the village shop, you can buy Riverhorses and the Zora's Flippers, which allow you to swim more quickly when you wear them.
In the house to the left of that, you can go into the hole in the floor and dive down to find some rupees under the floor boards.
Go east from the shop and go up the slope. To the east, there is a chest underwater that contains 20 rupees.
Go west, past the houses, and go up the slope. Go into the house, and there will be a cutscene.
Warp to the waypoint near the Smoothie Shop, then go north to Crossflows Plaza.
Go north and approach the Zoras, and there will be a cutscene. Go north and there will be another cutscene.
Use the map to warp back to the River Zora village. There will be a cutscene, and this will start the quest Chaos at River Zora Village.