Switch Palaces are the levels where you activate the different switches. Before the empty room with the switch, there are usually silver and blue P switches, and a lot of coins. Enter the pipe and the corresponding switch to the name of the coloured switch palace will appear in an otherwise empty room. Press it to activate. Here is the list of Switch Palaces and how to unlock them:
 Yellow Switch Palace
Beat Yoshi's Island 1. The level is simple. At this early stage, you might as well press the P-Switch to fill the screen with coins and get lots of extra lives for the journey ahead. It also contains Mushrooms when activated, and can be used for an extra ledge.
 Green Switch Palace
The secret exit of Donut Plains 2. I recommend that if you're low on lives, defeat the Koopas below for an extra life, but otherwise, enter the next room. The Green ! Blocks, when activated, will contain Cape Feathers, which are really useful, so this level is very important.
 Red Switch Palace
The secret exit of Vanilla Dome 2. I think it isn't too risky to press the P-Switch, especially if you're low on lives. Let the Koopa with the flashing shell defeat the eight Koopas, and collect the coins. The next room is waiting for you. When the Red ! Blocks are activated, it provides no items, but is useful as a ledge, or blocking an enemy from trying to defeat you.
 Blue Switch Palace
The secret exit of Forest of Illusion 2. I recommend Yoshi for this level as there is a bigger chance of you dying than surviving. Enter the next room, unless with Yoshi. Collect the coins, and then press the two P-Switches. You can get up to 2 lives in this level. When the Blue ! Blocks are activated, again there are no items, but it is useful as a ledge, or blocking an enemy from trying defeat you.
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