The Library is a stage where you learn about what happened to your pod - however, there are still plenty of enemies.
The Library[edit]
Swim to the left, and head down the first shaft. If you want to take a look at the library, take the first exit to the right, and sing at each glyph.
Within the shaft is a secret passage to the left. It leads to a statue - if you sing to it, you will be granted invulnerability for a few seconds. When it expires, you will have air and health restored to maximum.
The passage downward is blocked by a series of chains, and you will need a block to break them open. When you swim to the left, you will encounter one - as well as another statue you can use to gain invulnerability.
Push the block to the right. Whenever it falls into the pit, swim towards it, and face down. Turn upwards to lift the block; if it slips, turn down and up to catch it once more. You will need to repeat this three times, where it will land just before a ramp. At that moment, ram the cube and send it to the right - the box will break all four chains. If during this you start running out of air, or if you lose track of the box, swim up the right shaft before returning - the box should reappear to where it should be.
The exit[edit]
After the chains, swim and dash to the left. When you sing to the glyph, it will glow green and unlock the exit. Swim to the right, and you'll reach a moving platform, which leads to a room of jellyfish. The rooms leads to a vertical shaft, which you should charge through.
The shaft turns to the left, where you need to dodge the crystal-shaped spikes. Jump over the water, and you should reach the exit.