According to Baidu map, there are many special markets in Jinshan, Cangshan District, Fuzhou City, Fujian Province where you can buy hydrogen balloons. Hydrogen balloon is a kind of light bag-like or sac-like object filled with hydrogen, which is the lightest and has a density of 0.0899 g per liter. An object that can float upward by the buoyancy of hydrogen is called a hydrogen balloon.