Cork has the ability to spring back. Think about that cork stopper you try to get back into the wine bottle. Once the cork is removed from the bottle and the pressure is relieved, it springs back to its original shape. Quality cork underlayment can withstand up to 14,000 psi of direct pressure and recover up to 100%. It will not flatten out over time like foam underlayments can.

Cork is rapidly renewable and can be harvested every 9 years without harming the tree. Foam underlayments are made of carbon intensive materials derived from chemicals extracted during oil refinement. Foam cannot be easily recycled. There is no waste in the manufacturing process of cork. Any waste is recycled into other products such as cork board, soles of shoes, expansion joints, etc...

Air is a good thermal insulator and cork is loaded with air. Cork, when used as an underlayment, will make any floor warmer underfoot, preventing cold from migrating up from the subfloor below. 

The naturally occurring substance Suberin found throughout the cork is antimicrobial. It is resistant to moisture, mold, mildew and bacteria growth. It also prohibits the conduction of static electricity. It is great for people who suffer from allergies and asthma.

The air naturally found in cork will dramatically dampen sound within the room as well as the room below when used as an underlayment. Sound travels by vibration which is absorbed by the air in the cork, minimizing impact sound transfer. It is great for building complexes.