When you get to the merchant in the third chapter inside the docks, there will be an elevator to the right of him leading to the shooting range. Opposite the merchant there is a door. If you exit through it, you will find a pier with a motor boat. Go down closer to the boat and find an altar nearby that requires three hexagonal slabs (the rest are already installed).
Here is the location of the three remaining emblems on the lake:
The success of the title is quite expected.
New heroes, new challenges.
Deadpool's world is dying.
No release date for the adaptation has been given yet.