Trowels are obstacles found in Hey! Pikmin. They are found at the end of cliffs, standing upright, with the blade slightly buried into the dirt. Because they are upright, they block passage. Each time a Pikmin is thrown into it, it tilts a bit away from the cliff. When the trowel is tilted enough, it tips over, and the handle catches the cliff on the other side. This way, not only is the obstacle cleared, but it also serves as a bridge from one cliff to the other.
The first time a trowel is seen, at the First Expedition, a cutscene plays. In this cutscene, two Red Pikmin are itching to go to the other side of the cliff, but the trowel is in the way. One of the Pikmin tries to smack into the trowel to tip it over, but is too weak to do it alone, so nothing happens to the obstacle. This cutscene helps show the player that the idea is to smack the trowel enough times to make it fall over.