1. Conserve your air supply.If you are buried in a typical coffin, you will have enough air to survive for an hour or two at most. Take deep breaths, then hold for as long as possible before exhaling. Do not breathe and then swallow, which will lead to hyperventilation. Do not light a match or lighter. Combustion will quickly use your available oxygen. It is safe to use a flashlight if you have one. Do not yell. Yelling will lead to panic, which will increase your heart rate and lead to fast breathing that will rapidly consume your air supply.
2. Press up on the coffin lid with your hands.An inexpensive "pine box" (chipboard coffin) or a recycled paperboard coffin will have some give to it, so it will be relatively easy to break through. If you feel flex in the coffin lid, continue to step 3. A metal-clad or hardwood coffin will be impossible to pierce. In this case, your only hope is to signal for rescue. Use a metal object (ring, belt buckle, coin, flask, pen) to signal that you are alive. Tap SOS, the international distress signal, on the coffin lid: three quick taps, followed by three slower taps, followed by three quick taps. Continue to repeat the distress call until someone hears you.