Cave Entrance
Use SpongeBob to move the beachballs in the order shown (white 1-4) and collect top left Krabby Patties.
Next, switch to Patrick. Build a bridge using the two steel boxes as indicated (red 1-2), then place the third steel box on the blue button and Patrick on the white button. Spongebob can now collect the remaining Krabby Pattie.
Bonus Bubbles: Stand at the yellow "X" and time the tentacles. To be safe, wait until all three tentacles come up in unison.