This is part of the Flying Dutchman's Graveyard level. Once you reach the third area of the level, you'll talk to Mr. Krabs who will talk to you about the robot infested ship which has taken hold of the Dutchman's ship. As Krabs says, you'll have to head over to the robot ship to destroy some power generators, and then return to the Dutchman's to fire cannons.
Before going to the robot ship, be sure to bubble bust the button on the cannon right at the beginning of the gap. Maneuver your way across the gap, mind the Oiler that likes to camp this path, and start clearing out the enemies. There will be four generators on the robot ship's main deck. Destroy these, then go up to the traffic stop and use your homing missile to destroy the Duplicate-O-Tron on the other side of the ship. Go back down and bubble bowl the bowling panel. Do a 180, go back to the traffic stop and swap to Sandy quickly.
The bubble bowl panel you hit will bring a platform down. Get on the platform with her and lasso over to the fifth and final generator. Lasso your way back to the Dutchman's ship and switch to SpongeBob. Bubble bust the button on the cannon above the captain's quarters, use your homing missile on the button that's at the mast, then switch back to Sandy.
Use Sandy to jump up the platforms and the fourth cannon will be at the top. Activate it, and the treasure chest on top of the captain's quarters will open up. Go back to the traffic stop near it, switch to SpongeBob and bubble bust the button inside the treasure chest. This will trigger a cutscene, and the achievement will unlock.