Seaweed Shenanigans
Different colours of seaweed can be removed by stepping on the button of corresponding colour. Step on the yellow, blue, and red button and collect the nearby Krabby Patties. Notice that square buttons stay on once pressed.
The green button is round. Round buttons only stay on while someone (or something) is standing on them. You will often need to find a box to place onto a round button, in order to keep it active permanently. In this case, follow the green path to push the nearby box onto the round green button.
Repeat with the light blue button. Be careful not to push the box too far, as you cannot pull it away from a wall. A square white button controls the final group of patties.
Each level from here on will also contain Bonus Bubbles. These are never required to finish a level, but each collected bubble earns you 250 bonus points. They often require additional puzzles to be solved. In this case, some Bonus Bubbles are behind purple seaweed. Push a box along the purple path to open the seaweed gates permanently. Note that you always need to have collected your Bonus Bubbles before collecting the final Krabby Patties.