水筒 (すいとう) is a Japanese term that refers to a water bottle or thermos. It is commonly used to carry beverages, especially water, tea, or coffee, making it convenient for people on the go. 水筒 can be made from various materials, including stainless steel, plastic, and glass, and often features insulation to keep drinks hot or cold for extended periods. In Japan, 水筒 is popular among students and outdoor enthusiasts. Many schools encourage students to bring a 水筒 to stay hydrated throughout the day. Additionally, during activities like hiking or picnics, a 水筒 is essential for carrying enough liquid to stay refreshed and energized.