Getting the Whip
Go up into the Temple. Inside, go up and left. To defeat the Electric Chu-Chus here, stun them with the Boomerang, then finish them with the sword. Here there are four signs. Record the numbers given on the signs on their locations on the map. Continue north. Run through this corridor to avoid the arrows, then turn north and up the stairs. Upstairs, go south and left. Stand on the brown platform, facing north. The platform will carry you across the abyss, but face north so your shield will protect you from the arrows. Step off and go south. Here is where you need the order from the floor below. Step onto the platform and strike the switches here in that order. When you strike them in order with your Boomerang, the blue door will open. Go right, but don't go north. Stop just before the floor changes colour, and send your Boomerang up there instead. You should see a purple switch, so strike that with the Boomerang. This closes a trap door, and opens another one just in front of where you're standing. Go back downstairs.
Near the entrance, where you turned left, instead go north and right. Now that the trap door upstairs is closed, the boulders pass over the corridor, and instead fall into the hole. Go north-east and up the stairs. Here, go south, turn right and go up the stairs. Go left. In here, an enemy with a whip, the Snapper, will grab you. Wait for him to pull you in close, then attack him. Repeat this until he is dead. A large chest will appear containing the Whip! Equip it straight away. To use it, touch its icon, then tap the area or object you want to whip. Go through the door to the west. To cross the abyss, whip the brown post and Link will automatically swing across. Go up the stairs. The sign says, 'Grab the farthest ring from your grasp.' Go south, cross the abyss with the Whip, and continue east. Near the closed blue door is a statue with a ring in its mouth. Grab it with the Whip. Go through. There are three thin paths. Look at the map. Remember that message on the sign? Go up the shortest path. Grab the ring there, and a bridge will appear. Cross it and go down the stairs.
Go left. There are two statues, one with a ring in its mouth, the other with an open, gaping mouth. Grab the ring with the whip. Tap the open-mouthed statue to throw the sword you get into its mouth. Open the chest that appears for a key. Cross the abyss with the post that also appeared, and go through the north door. Cross the abyss, and go left. Unlock the door and climb the stairs. To the left, pull the ring to open a door that creates a shortcut if you need to leave the dungeon. Go right and cross the abyss. To cross these posts, tap the next one when Link swings near to it. Go south. These enemies are defeated by whipping them to remove their armour, then whipping them again to finish them. Go up the stairs.
The green barrier here is opened by whipping the spikes, then throwing them away by tapping another area. Go through. The sign tells you, 'Three blades sit in a row. Retrieve them all to open the path.' Go back out and go west. Here, there are two Snappers. They are easier now you have your own whip. Whip them to make them dizzy, then attack them with the sword. Go to the path to the left in the centre of the room. Here are the three blades that the sign spoke of earlier. Grab them all, and a series of posts will appear in the north of the room. Continue left and north. Grab the ring here to create a helicopter-like apparatus. Grab the red ring and don't let go of the touch screen until you reach the area in the south-west corner of the room. Go up the stairs. The electric Chu-Chus here can't be defeated like the yellow ones. At the top of the room is a statue with a blade. Grab it and throw it at the Chu-Chus to defeat them. A post will appear in the other side of the floor. Go back downstairs. Get the helicopter here back to the main area of the floor. Go to the north-east corner of the floor. Cross the abyss with the Whip and posts and go upstairs. Cross with the posts here. (You'll have to drop down a bit before grabbing the last one.) Hit the switch (you'll need it later). Go south and west. A sign says 'Remember the placement of the blades.' Look at the statues here. Two have blades, three don't. Record this (3, 5 have blades, or something similar.) Go to all four possible paths of the room and do the same. In the bottom right path, cross the abyss at the east end for a small key. Go back downstairs and cross the abyss.
You should have seen some statues with blades here before. This is where the orders you recorded upstairs comes in. In the locations directly below where the blades are in the orders recorded, manipulate the blades here into the same order. For example, in the top right, the blades upstairs are in the 3rd and 5th statues. You need to put the blades in the 3rd and 5th statues in the top right on this floor using the whip. When they are in the right order, a door will open. Go to the south of the floor and unlock the door. Cross the abyss and go up the stairs. Grab the helicopter and hold onto it until you are above the brown platform. Get off where the Boss Key is. Stand on the floor switch. This creates a bridge. Grab the Key. When you step off the bridge, four hands will appear. Drop the Key and kill all of them. Pick it up and walk towards the Boss Door. When you get near it, another hand will appear. Drop the key and kill it. Grab the key, go up the stairs and open the door. Go left here. Cross the abyss. Go left again. Check the nearby sign to open a portal to the entrance. Staying here, clear away the barbs at the staircase, save your game and go upstairs.
Boss: Cactops (Phytops), Barbed Menace
When you enter, the door will close behind you. There are several abysses and whip posts that you need to clear. At two points on the way up, you'll see a tentacle with spikes and an eye. Grab one of the spikes with the Whip, and throw it at the eye to defeat the tentacle. Be wary of pink poisonous liquids falling on top of you as you climb. At the top, grab the helicopter and go up to meet Cactops/Phytops, the Barbed Menace. It will smash down on the ground with its tentacles. When you land, grab a spike with your whip and throw it at the purple bubbles above its mouth. Do this twice to reveal its eye. Do this again to the eye to knock it out temporarily. Run around and strike it with your sword as much as possible. It will dive into the pool and re-emerge with four tentacles. Try to avoid their attacks. The tentacles will dive and Cactops/Phytops will return. Do the same again to reveal and attack its eye. The four tentacles will re-appear and attack, soon joined by Cactops/Phytops itself. You now need to avoid the pink liquid it spits at you as well as the attacks of the upper two tentacles, all while trying to reveal its eye and attack it as before. As it gets weaker, it will start to rotate as it attacks you. Just repeat the process until you defeat it.
As in the other Temples, the Ocean Source will come to rest on its pedestal, the energy will travel to the Tower of Spirits, and the next section of the Tower will be restored. The tracks leading to the Tower will appear. A chest containing a Heart Container, and a portal to the Spirit Train will appear. Get the Heart Container and leave. Prepare to return to the Tower of Spirits.