The scuba tank cart is a scuba transporting apparatus that provides a device for storing a scuba tank, transporting the tank, and using the apparatus as a tank flotation device for diving and snorkeling. The cart has a roller, a cavity to fit a scuba tank, and a bracket to store a hose and regulator. The cart is designed so that when the cart is in the water, the cart floats horizontally to support the tank above the water while the user is underwater carrying only the hose for breathing.