How to get past Tropical Wilds in Pikmin 3?

So I finished the Distant tundra level, and my game kept telling me to go back to Tropical Wilds. I am unsure of what to do now, since I already searched it thoroughly. Is there a secret passage to go to the next world or something?


Solution 1:

Now that you have rescued Charlie, you also have access to the yellow pikmin. Use these to break down an electric wall, where you have access to more things, such as blue pikmin.