Sukumizu (スク水), short for school mizugi , is a variant of swimwear intended for use by school students during swimming lessons in Japan. They can come in the form of either a one-piece or a two-piece swimsuit for girls, the latter of which corresponds to a sleeveless shirt for the upper torso. Boys, on the other hand, generally wear swim trunks. They are usually coloured in a dark blue hue, are closely fitting, and have typical seam lines that run laterally across the chest for girls. The material is generally a mixture of synthetic fibers such as nylon and polyester.