Maybe I just hang out with some strange people but more than once I have heard people remark about the foolishness of spending thousands of dollars to buy a hermetically sealed water proof time capsule for a coffin, that is most likely not very eco-friendly. When all you really need is a simple cardboard box. It seems UK based Ecocoffins and Australia based Life Art have the answer. They are makers of fine cardboard based coffins.
Given enough time anything you put into the earth is just going to rot away, so why fight nature. Just drop yourself in one of these sturdy cardboard boxes (if its good enough to ship that $10,000 flat screen TV its good enough to ship you) and your ready for the great adventure in the sky.
Ecocoffin in particular makes a very green product.
They are made from cardboard, but are unlike any other cardboard coffin on the market. Made from 90% recycled material, a rigid honeycomb construction provides strength and stability whilst being 100% biodegradable. Our product has been tested at crematoria and at traditional burial sites and are suitable for both.(via)