Destroy the boat lying upside down  and build a new object using the bricks. 
Take the spade hitting the skeleton lying near the rock.  Now look for the upper object on Jack's compass. 
Dig up the object and destroy the lock.  Inside there is a chest. Take it to the right to the path in check pattern. Put aside the box for a moment and push the object previously assembled into water (to make way). 
As a character with the sword activate the mechanism that lifts the bridge.  Use the second character to move the chest along through the islands and put it in the given place.  Use the bricks to build a new object.
Switch to Angelika and go right. You will find a place to perform a double jump.  When you are up turn the winch on the left to lift the ladder for your companions. 
Go upstairs and open the door as Garheng.
In the tower go upstairs and take the torch.  Set on fire the object on the left (on the upper floor). 
Go downstairs and repair the mechanism (Salaman).  Next turn the mechanism in the center (pushing the green or blue side of the brick) to place it in the pipe in the ground on the left. 
Use the helm so the arrow indicating up above the given pipe was green.  When the setup is ok run upstairs and set on fire the mechanism using the torch. 
Repeat the action with the two other pipes.  Go back upstairs and use the lens with the spyglass.  Observe the swimming mermaid.
Coming back to the bay
Jump down and go left - you will see how the mermaid destroys the crystal.  Go back and turn right and climb the tower using Jack's hook. 
When you are up move the wheel to pick up the dynamite.  Put it on the green floor panel. 
Go back at the very beginning of the level and look for the boat on the shore.  Jump in it and sail with the pirate to the platform. Pick up the dynamite and get to the shore. 
Move the dynamite using the planks  and put it on the elevator. 
Get to the tower and repeat the action with pulling out the dynamite. Put the chest on the other green floor panel and then put the explosives on the wall.  At the end set everything on fire using the torch.