What is the cheapest method to transport heavy goods and materials?

The cheapest method to transport heavy goods and material is through cargo ships by the sea for long distance carriages. But this method is time consuming and not as flexible as other methods of transport. You can mostly only send bulky non perishable heavy goods by this method of transport and you cannot rely on this method of long distance transport if you are sending products that are in high demand in market as it is time consuming.