Three-quarters of the earth's surface is covered by water, probably the most frightening of all environments, and the most difficult in which to survive.

Skipper Bobby Lambe's 20-hour ordeal on the high seas after his boat, New Nuts, sank due to a freak wave, is nothing short of miraculous.

The quick-thinking Mr. Lambe was able to cling to a large piece of wood and grab a bottle of Red Devil energy drink. These two things helped him survive for the 20 hours until he was spotted by rescue airplanes passing overhead and picked up by the passing American naval medical ship, the USNS Comfort.

Every survival situation is different, and will call upon all of a survivor's resourcefulness and creativity. The most important thing, stress the experts, is to stay calm. Every single effort should be concentrated on staying alive: one has to hope for the best, but prepare for the worst.

Mr. Lambe, an experienced fisherman, was able to stay calm and alert in his survival situation. So just what should you do if you find yourself in a similar situation of having to survive at sea?

The first priority, if the boat or airplane is sinking, it to get clear, or it will pull you under. You should swim upwind. If there's a chance of an underwater explosion swim on your back, as that minimises your chances for injury.

Once the boat/airplane has sunk, go back. Your first job is to find something to help you float and keep you protected from the elements.

The second is to gather anything else which might be useful: any fabric, containers, emergency rations, signalling equipment, etc.

Once you have gathered everything you can and have gotten your bearings, take inventory of what you have. Begin rationing your water and food right away.

Protecting yourself from the elements is the number one priority. Your resistance to the elements will have been weakened by fear, stress, and energy loss.

The primary causes of concern will be drowning and hypothermia. To prevent drowning, either grab something you can float on or stay relaxed. If your body is relaxed its natural buoyancy will keep you afloat.

Float on your back or, if this is not possible, on your stomach with your arms spread. When you need to breathe, push your arms down to lift your head out of the water only as long as you need to take a breath.

Conserve your energy and float as much as possible. Relaxing and controlling your breathing is the key.

To prevent hypothermia the best thing to do is get out of the water. You lose heat 25 times faster in water than you do out of it.

If you cannot get out of the water, save your energy. Movement in cold water will increase blood circulation and therefore heat loss - it will not warm you, it will actually make you colder.

Grab whatever clothing or other fabric you can find to keep you warm. In cold water especially it is more important to grab clothing than food. You can also use air trapped in clothing or fabrics for buoyancy.

Protect your eyes from the sun by covering them with clothing with slits for eyeholes. Protect yourself from the wind and sun. Stay as dry as possible, especially during the night.

Your next priority, after protecting yourself from the elements, is water. If you have food but do not have water, do not eat. Digestion requires a lot of water, and it is possible to survive much longer without food than water. Make sure you have water before you eat.

You can reduce your water loss by preventing sweating: stay cool. If you get motion sickness avoid vomiting as this causes loss of valuable fluids.

On your first day you will still have lots of water in you so you will not need to drink. After the first day, ration your water. Before drinking, moisten your lips and tongue. Do not drink seawater, urine or alcohol, as they will increase dehydration.

You can collect rainwater in any containers you have managed to salvage, or in fabric that has been rinsed in the ocean to prevent salt build-up.

Keep all your equipment up to catch rainwater as you sleep. Any large surface will also work for collecting condensation over night.

Drink slowly, and store as much fresh water as you can in whatever you have available.

Once you have secured a means of getting water, your next priority is food.

Carbohydrates require less water than proteins for digestion, so you should eat whatever carbohydrates are available first.

Start fishing as soon as you can. Night is best for fishing. Use whatever you have available to attract fish, including anything shiny or reflective. Most fish on the open ocean are edible.

All sea birds are also edible, as is most ocean vegetation such as plankton.

Always make sure you have water, however - remember digestion requires water and if you do not have water available, it is best not to eat until you do.

Finally, your last priority is finding the best way of attracting rescue. Obviously this is easiest when you have signalling equipment, such as an EPIRB, radio, GPS system, or flares.

If, however, you do not have any signalling equipment, you will have to use your creativity. Anything colourful or reflective can be effective for attracting rescue. Do not rule anything out - even a message in a bottle could save you.

Always have your signalling devices ready for instant use, as you never know when a plane or a boat may pass by.

And finally, remember: having the skills to survive are important, but having the will to survive is essential.

More information on surviving at sea can be found online at http://www.caske2000.org/survival/survivesea.htm or

http://www.survivaliq.com/survival/sea-survival.htm.