There is a ton of breakable stuff on this level including all the glass-covered cases and busts along the walls. Head down the hallway and grab the two clue bottle before going through the red skeleton door. Wait for the lasers to bunch up and move to the sides or above you to get through the next four barriers and take out the red siren at the end. Grab the bottle on the right before venturing out into the open area with the flaming skull in the background. As soon as you go down the ramp the skull will shoot its laser eyes out at you and they will follow you all over the room until you break the security siren beneath it. Avoid the lasers following you and head to the left, then run through the middle laser barrier and head straight for the siren. The way you don't have to run up and down the path between the barriers.
After you take out the security, break open the mini-safe by it for two bottles, then go off the left side of the stairs to find three more right below. Next go all the way across the room for three more on a little platform off the side. Back at the top where the siren was, break one of the stone frog statues and use the base to jump up above for two more bottles. On this ledge, head away from the center and circle around to the other side where you'll find another bottle behind the big skull's head. Keep going around and get the other two bottles above the other frog statue. Now you're ready to jump down and continue through to the next area.
There are two more mini-safes and two belly flop bad guys on the ramp down to the water. Wait for them to land, then run up and whack them with your cane. You will get four more bottles from the mini-safes, then you can start moving on. Off to the right is a lone platform with an extra life on it, and straight ahead is the next platform with another clue bottle. From the platform with the clue bottle, you'll need to jump from lilypad to lilypad around to the red siren, going counterclockwise. While doing so, you also have to jump over the spinning lasers going around in the opposite direction. There is a bottle halfway around the lilypads, but it might be easier to go break the siren and then come back for it. The trick is to time your jumps so you can use your double-jump to get over the lasers.
After breaking the siren, climb up the pole and thief walk around the first pillar for two more bottles. Head down the path and run between the spotlights after the next column, getting two more bottles in the process. Thief walk around the next two columns, then run between the spotlights and break the red siren to turn off security. Go back and get the two bottles by the last two spotlights if you didn't already, then get two more by thief walking around the final column. You're now right below the key, but with the last bottles in your possession you can now open the safe back where the big skull with the laser eyes was. Depending on what you think is easier, you can jump back down to the lilypads and go back for the safe, or get the key and redo the level up until the safe.