Solved
Google Play Coconut Cannon achievement
Pirate Seas Day 22 - activate Google Play (main screen bottom right corner) before going to Adventure Mode Pirate Seas Day 22
Select Coconut Cannon as one of your plants - I like to use Tile Turnip, Hot Date or Sweet Potato, Blover, Jalapeno (duplicate if you have Imitator), Laser Bean, Squash Use with a Tile Turnip)
Put down at least one Coconut Cannon and use it to destroy the first IMP cannon - Achievement rewarded !
EDIT spelling/typing
The Achievement is called "Broadside"
I had to use a Plant Food on the Coconut Cannon to take out the IMP cannon but it worked !!
