Liferaft is a small, rigid or inflatable boat carried for emergency evacuation in the event of a disaster aboard a ship. Recreational sailors usually carry inflatable liferafts, though a few prefer small proactive lifeboats that are harder to sink and can be sailed to safety. Inflatable liferafs may be equipped with auto-inflation (carbon dioxide or nitrogen) canisters or mechanical pumps. A quick release and pressure release mechanism is fitted on ships so that the canister or pump automatically inflates the lifeboat, and the lifeboat breaks free of the sinking vessel. Commercial aircraft are also required to carry auto-inflating liferafts in case of an emergency water landing; offshore oil platforms also have liferafts.