Changes

A version difference here gives an advantage of about 5 seconds to Dreamcast players.  On either system, the fastest path involves collecting all three keys in the same life.

A version difference here gives an advantage of about 5 seconds to Dreamcast players.  On either system, the fastest path involves collecting all three keys in the same life.

Start this mission out just like you would mission 3, keeping in mind the added enemies.  Do not try to get out of bounds at the corner light; it doesn't help (you can easily see the room you need to aim for, but it's a bit too high to reach from here).  Instead, drop down a level, punch out the hourglass, and dig into the mural on the right side of the next room.  After you dig through the mural, you're in the room with the first key.  On Dreamcast, you can just stand over the middle of the hourglass floor and do a Spiral Upper to pull the key out directly.  On GameCube, you'll have to hit the hourglass,  go left or right to stand on the platform that appears, punch out boxes, hit the next hourglass, and dig into the middle of the now-opened ground to get this key.

Start this mission out just like you would the easy path on mission 3, keeping in mind the added enemies.  Do not try to get out of bounds at the corner light; it doesn't help (you can easily see the room you need to aim for, but it's a bit too high to reach from here).  Instead, drop down a level, punch out the hourglass, and dig into the mural on the right side of the next room.  After you dig through the mural, you're in the room with the first key.  On Dreamcast, you can just stand over the middle of the hourglass floor and do a Spiral Upper to pull the key out directly.  On GameCube, you'll have to hit the hourglass,  go left or right to stand on the platform that appears, punch out boxes, hit the next hourglass, and dig into the middle of the now-opened ground to get this key.

Now dive through the corner into free space again, and continue to the center room and follow the walls around to the underwater hallway.  You don't need to rise all the way to the top this time.  Stay under the walls of the underwater mirror of the Chao room, and swim until you're under the center of the lower alcove.  The next key is inside a closed hourglass door, but you can shoot up through it to get back in bounds and collect the key.  From here it's a short trip to the last key by heading out into the main room, going up, and diving down behind the chest in this room.

Now dive through the corner into free space again, and continue to the center room and follow the walls around to the underwater hallway.  You don't need to rise all the way to the top this time.  Stay under the walls of the underwater mirror of the Chao room, and swim until you're under the center of the lower alcove.  The next key is inside a closed hourglass door, but you can shoot up through it to get back in bounds and collect the key.  From here it's a short trip to the last key by heading out into the main room, going up, and diving down behind the chest in this room.