A clog is an obstacle in Pikmin 2 and Hey! Pikmin that looks like a cracked rock, used to block the entrance of caves and geysers, and to plug holes underwater so that areas remain flooded. They can be destroyed with Pikmin; often, only Blue Pikmin are able to approach them due to them being submerged. By destroying an underwater clog, a hole is opened up that drains the water from the surrounding area. However, clogs also appear on certain caves, and block the hole that leads to the next sublevel.