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This chamber is about using both portals to climb up to the top of a tall room consisting of several different levels on alternating sides of the room.

…f…fling yourself…need to fling into spa…

—GLaDOS

As with previous climbing puzzles, the trick is to get the momentum. In this case, a pit at the bottom of the chamber allows for that, so place an orange portal () in the middle of it. You'll need somewhere to come out, and the panel opposite the level above you allows for that; place a blue portal in the middle of it. Now, simply fall into the orange portal, and you'll end up on the first level.

The same can be done to get you onto the second level, re-using the orange portal in the pit, and placing a new blue portal on the next set of panels.

You'll notice there's a button on the second level. Before you can access the chamberlock, a cube will need to be taken from the third level, brought back to the second level and placed on the button.

Do the same as the last two times to get onto the third level. Now, pick up a cube and fall back onto the second level. The cube needs to be placed onto the button, and then you need to repeat the journey through the portal to get back onto the third level and enter the chamberlock.