Get through the plants to get into the open space.  As the female character jump on the rocky shelf grabbing the green bar. When you are up hit the skeleton and take the spade. 
Use Jack's compass to find the treasure - the spyglass.  Destroy the box, assemble the object and take it to the green panel. 
Use the spyglass and follow the trickle of water.  Enter the cave. 
In the cave go on the right till you reach a huge spiderweb. Hit it few times till the bricks fall down.  Use them to build a lantern. 
Look for the barrel on the right and use it to turn the mechanism near the lantern.  Go to the right behind the corridor leading straight into the cave and grab the chain (Angelika). 
Move along the corridor and use Jack's compass to find the third lamp.  Use the spade to dig it up (it is on the left) and assemble it. 
Take the wheel to the mechanism and activate it.  Jump into the puddle with no gravity. 
Explore the cave with the Fountain. Against the opposite wall you will find the brown objects lying on the path in the check pattern. Push one of them to the wall and the other one push into water on the left.  Go on the right and use Jack's compass to find the chest with the bombs. 
Throw the bomb at the silver bricks.  Rebuild a ladder out of them and climb. Take the mermaid's statue. 
Take the mermaid's statue through the lake using the wooden planks and put it on the green platform on the left.  Push the statue straight on the geyser. 
Go to the left part of the map and use the compass to find the other statue.  Dig it up and assemble.  Push the statue on the other geyser.
When the pillar falls down head to the central island.
Blackbeard attacks with red bolts that reverse the steering for a moment. Dodge them and wait till he jumps down. Attack him with the sword.  Siren will jump from water. After the cut scene give her the goblet which stands on the right. 
Avoid Blackbeard's bolts and wait till he jumps down to fight. Again attack him. When you hit him with the sword you will stun him.  When that happens quickly take the goblet to Angelika who sits at the top of the stairs.  You need to repeat that action 4 times.
Eventually the opponent will throw the chests at you. Wait till a bomb will fall from one of them. Grab it and throw it at him.  He will come down and you will be able to stun him again (and give another goblet to Angelika).