How do you get past fire in Pikmin 2?

The question's just a little vague, but here goes. Well, first off, the only type of Pikmin that can actually travel through water safely is the blue Pikmin. If you're trying to get other types of Pikmin across, there's a number of things to do. First off, see if you can't find a bridge to roll out. Or, and this is a bit risky, if the body of water isn't incredibly large, you can throw some Pikmin in, then try to use the whistle to call them to the other side. This is, however, quite dangerous, and I wouldn't recommend doing it without first knowing that it's possible.