One of the first rules of survival in general is there are no rules. The amount of variables is inconceivable and impossible to predict. Survival in one geographical area may totally differ in another. For example, you wouldn’t do the same things to survive in the desert as you would in the arctic. Keeping that in mind, I will run down a possible scenario based on the deserted island concept. We will say that this island will be located somewhere tropical seeing how everything we see on TV related to this subject seems to take place in that type of climate.
First and foremost, the body requires one thing more than all others to survive…water. Without water, we cannot make it more than a few days in almost a region. In some extreme cases without water, we will be lucky to make it a day. That being said, should you find yourself stranded on a deserted island, the first thing I recommend doing is finding a source of fresh running water. Fortunately, in the tropics there is a fair amount of rain thus generating a good supply of fresh water.
Stay away from stagnating bodies of water, they usually contain high amounts of bacteria and parasites. The tropics are a breeding ground for bacteria due to the warm, damp climate so be careful what you drink. Also, keep in mind that fear of dying from lack of water will sometimes force you to drink otherwise undrinkable water. Use this as a last resort however, the sickness you will no doubt develop will have you in worse shape than you would have thought possible.
If you find yourself washed ashore on an island, walk the beach looking for water ways leading to the ocean. There is a good chance that this water will be fresh water and if you follow it, you will usually find faster moving water further inland. This will also lead you to edible plants, animals, and insects. They all seem to be around each other. The plants grow by the water, animals need food and water, and insects need animals and plants to survive.
My next bit of advice is to forget everything you know about what you like to eat and start thinking about what is available to eat. Your survival will depend on this if you are stranded for any length of time. Most insects are edible though not my first choice in a pinch. There are a lot of edible plants to pick from first. You can eat leaves, berries, roots and even the bark of some trees. However, some plants are also very poisonous and if your unsure about what can and cannot be eaten, you might want to stay away from plants.
Now let’s talk about animals…pretty much any animal you can find is edible. The hard part is catching them. Use rocks, sticks, rope, vines, shells, or anything else you can find to make some tools and weapons. You can use wreckage from a boat of the plane to help with making tools and you may even be able to use it for shelter too. Snakes! Snakes are prevalent in the tropics and literally every single snake on the planet is edible whether poisonous or not. Snakes are fairly easy to catch and kill, but I do have one word of caution. Most tropical snakes are poisonous, so be careful when dealing with the weather looking for them or running across them on accident.
Finally, we’ll talk about the importance of fire, and how it will make your life much more comfortable once you’re able to obtain it. Anyone who has tried to make fire from rubbing sticks together can tell you, it’s not easy. There is definitely a degree of skill and knowledge working together here. Dry wood is a good place to start and when I say dry, I mean not green. It needs to be dead and completely dried out. You must also start very small and build up to larger pieces from there.
The fine hair from coconuts is a good place to start or strip bark from dead dry trees. Then have a good supply of dry twigs and branches and finally some nice sized pieces of wood if you have the means of getting it. Have everything you will need right there so you not running around looking for stuff as you go. This will save you a lot of time and heartache. Fire is important because most everything you find to eat is better tasting and better for you if cooked, especially water. If you boil the water before drinking, it will kill all of the harmful bacteria. Staying warm is also important and fire will help you immensely in that aspect.
So if some day you should find yourself stranded on a deserted island, hopefully this will help you stay alive and more comfortable until help arrives.