The button here will take you higher, use it and then go ahead to the last button to move a number of gears which eventually opens the door into the castle.

Here interact with the first button on your left, then head to the button on the gate and interact with it to lock you into a small area, from here go into the new area and use the button there, it will move another wall over, then head through to where it was and interact with the button on the floor and it will move a wall revealing a bubble, jump into it to get to the next area. There is also a Blue Trinity here, but now head back and go left. 'Call' to get into the Dungeon, there are two chests here both containing Float-G. Now from here head into the bubble on the left to go further in.

In this room there is a Save Point with a chest to its left, open it to get a Firaga Ring, then 'Call' to clear the way. Head back to the Base Level and jump into the bubble on the right to get back to the Waterway. Head in and open the chest to get an Esuna-G. Inside you'll find a wall with iron bars, 'Call' and The Beast will clear the way. If you spot a chest on a platform to the right, open it to get a Tornado-G then head back to the 2 extended platforms and go through the exit to the Waterway. You'll have both platforms extended and can easily get across. Glide from the left side onto the other platform and use the other ice switch and 'Release'. Turn around for a chest, open it to get a Tornado-G. Jump to the ice switch and 'Release', it will cause a platform to extend out of the wall. Jump into the bubble on the left to go to the other half of this area and jump onto the platform, then backwards to get to a chest, open it to get a Mythril. Then examine the other to go down to the Base Level. Examine the switch near the wall to cause a hanging platform to move. Now from here, head right and the gates will open to another section of this area. Now jump to the two moving platforms and head to the Castle Gates. Glide to the chest just behind this platform to get a Megalixir. Now that you have a weak weapon, you must rely on The Beast and items. Sora and The Beast join together to get their loved ones. Donald and Goofy leave Sora to follow Riku as he holds the Key. Soon Riku takes the Keyblade from Sora, and calls him the 'delivery boy'. Riku avoids The Beast's hit and attacks him back and The Beast falls to the ground when Sora appears to stop Riku. The Beast is there and claims he simply believed to find Belle and that his world fell into Darkness once she was taken. Then glide ahead to the platform with an arch for a cutscene. Now head back to the same bubble but this time freeze it with magic and jump onto the platform to the left and open the chest there to get a Blizzaga Ring. Head over to the 3rd bubble and get in it and you'll find a chest underwater with a Dispel-G inside it. Jump down and open the chest above the water to get Dalmatians 91, 92 and 93. Once you're in control, save and freeze the two bubbles with Blizzard and jump on them to the chest to get a Dispel-G. Once you land Sora will feel a warmth inside, as if he's been to this place, Donald makes it out that Sora's hungry, but Sora blasts out that he's serious, then a roar is heard.

Kingdom hearts 1 hollow bastion