My question, as well. There is a big difference among those environments.

just for fun, let me jump in and suggest an actual island that has been deserted during historic times - San Nicolas Island, off the coast of Southern California. It currently hosts the US Navy, whose biggest issue today would be a beverage shortage in the PX.

It is renowned as the location of the 'Lone Woman of San Nicolas Island," who lived alone on the island for 18 years during the 19th century. AFAIK, she had none of the items available on our proposed list.

San Nicolas does have some permanent springs, productive tide pools, and edible native plants. Much better climate than those frigid, windswept Alaskan Islands....

Hmmm, still thinking, trade-offs and combinations. FWIW, the knife pictured is a Mora in high carbon steel so could be used to start a fire if the right rock is available.

My point exactly. These tarps are an incredible source for zillions of improvizations, easy to setup and take off, and incredibly heavy duty! You can cut a piece and have no noticeable impact from that on your shelter, contrary to any tent (many folks above plan to cut something from the tent and still retain its bug/weeatherproofness properties after that, but even if you use only the rainfly for something unusual - you can quickly ruin its waterproofness really easy with the typical PVC/urethane coating used for that). Besides, the tent pictured is really not suitable for any serious shelter from elements, as that's the cheap Wnzel Alpine 3 person tent: http://www.amazon.com/dp/B002PAT60S even the rainfly on it is a joke

The FAK could be definitely essential if we know its content. The one pictured, is quite a good one actually (but not ideal, as Jacqui expecting): https://www.optomo.com.au/product/sports-first-aid-kit/ However, I would adjust my kit replacing the mirror with it. So my revised list would be:

Tarp, knife, FAK, flashlight.

A flashlight is better for the night signaling because you can use morse code to convey your message clearly and effortlessly any moment and to any direction (imagine that you heard a ship/plane/copter coming in the vicinity of the opposite to your shelter side of your densely "firewooded" island (tall trees), where you can run, but cannot bring your 3 piles of wood quickly). Also, with the signaling fire, you need to build and feed 3 of them (distress signal) in a wide enough row every night - that's a lot of resources and energy to spend (still doable, granted the island provides plenty of resources to replenish that energy daily).

By the way, I saw a lot of hype on preppers resources about the importance of having a glowstick, which being spinned on a cord should create a "highly visible glow ring" for signaling. However, from my astronomy (and thus light physics and visual perception) experience, a concentrated bright point is much more visible over a greater distance, especially compared to the barely visible glow produced by the chem.stick, dispersed over a large field of view (some may recall the laser beam test explained here a while ago supporting that as well). The wider motion of the light might play a role here, though, so if in doubt, I'd rather hold my >100 lumen flashlight with a long leafy branch in one hand and wave it around making sure it's well illuminated. Or I can illuminate in a SOS morse pattern a well visible from around tall tree instead. A green laser could work great for that as well, if you shake it in a fast "scanning" motion over the tree branches (had heard a loud "wow!" from the half a mile over the lake campground once, when played with my astronomy green laser that way at night, perhaps, thy thought it was an UFO landing ).

Another nice "flashlight on a rope" night signaling technique, I'm aware of, is great for the wide open horizon: attach it by the rear end to a 6-7' rope, make a knot (or a finger sized loop) at 2-3' and at the other end. Hold it over the shorter khot and swing the flashlight above the head, making sure it goes close to the horizontal plane, exactly 3 times, quickly switch to the end knot and swing 3 more times. Repeat until tired. That will create the well recognizable SOS beacon, efficiently visible to distant observers from every direction around you.

I'd never heard of that before, very cool!

Hard to tell, but that tarp in the image does not look all that big. I would guesstimate it to be at the smallest, a 6x8' or at the largest, 6x10'. Either size is too small to be much use in providing an adequate and walled shelter from rain, wind, bugs etc without some serious work.

Cheap tent or not, I still would choose it over the tarp without hesitation. Having a readily sealed shelter from the elements (wind, sun, rain and bugs) makes it a much better option then a tarp any day.

We have a similar "cheap" tent that my neice used when she tagged along with us on camping trips. That cheap tent has easily, 75 sleeping nights in it. So far, the tent has survived rain, snow, wind, flood and to this today, I would not hesitate to use it again for camping - or in a true survival situation. As for the tent fly itself, it measures 45" x 35". Not the largest, but I can think of plenty of uses for the fly in the same survival situation.

In that case:

Record lows are above freezing, but not by much, so shelter is a must, but could be improvised with local materials or an improved cave.

Fresh water sources, so the water filter goes down on the list.

Much of the available food can be eaten without cooking, but cooking would still be preferable.

A tarp is very versatile. Signaling can be done with local materials and fishing can be done a variety of ways.

So my choices:

Tarp
Pot
Rope
Knife

You are probably right, 6x8. Found it here http://stormprepare.com/Tarp.htm I hoped it's at least the one pictured above it on that shopping list..., still, you cannot make a raft out of a tent:



By the way, another wonder from the same russian guy, where instead of tarp he is using the polyethylene wrapping film.



2000' of that can be had for just $15, and provide a lot of interesting options, including quite a nice shelter:



The best deal I've found so far (in US): http://www.ebay.com/itm/172068497146

We all seem to read various elements into the descriptions of the items on the list and make assumptions - the tarp is a certain size, the tent is a given quality, etc. I would repeat my strategy of searching for a cave, rock shelter or equivalent for shelter. I suggest this not just because the rock shelter might provide acceptable housing; there is the likelihood that the right cave will provide excellent refuge, superior to any tent or tarp.

I say largely because of my experience in Canyon de Chelly (NE AZ). There I spent a number of years excavating and exploring interesting cliff dwellings - one of which I dug for over four years. I noticed that the cave received early morning light, welcome warmth even in the summer. About 11 AM, as the sun climbed higher, a shadow lengthened from the back of the shelter, eventually enveloping the entire dwelling in welcome shade. Rain and snow were no problem. One winter I backpacked into the site, noting that solar radiation was growing an early crop of green grass in one area near the building - something I'll bet those early farmers used to good effect.

One year, I had to sleep at the site for several nights and it was a thoroughly enjoyable experience. I have had comparable times at other shelters throughout the western US and I prefer a suitable rock shelter to any tent.

Generally, the best shelters are those facing south and east (in the northern hemisphere). The Lone Woman of San Nicolas Island apparently made use of at least one such cave on her island.

Take your tent, its cordage, stakes, and poles, as well as your tarp, and recycle them once you have found the cave of your dreams.

BTW, threads like this are very fun exercises that can really get you thinking about survival! Choosing four items is arbitrary, and anyone that hangs out at ETS will hopefully be better prepared than that, but it does help focus priorities.

In my mind a tent would be huge! Obviously a lot camper might have a tent along already as part of their normal load out but otherwise it's bulky enough that almost no one would carry one "just in case". That said, I think having a tent is huge psychologically. Being in a tent does feel like being indoors, making one much more comfortable in strange surroundings. A good test provides a lot of protection, too. It offers protection from the elements (keeping you dry) and protects from convective cooling (the wind blowing on you). It won't hold in a lot of heat but it will prevent many kinds of heat loss. Great for keeping the direct sun off of you, too.

Okay, I'll play.

Handsaw. Tent. Pot. Matches.

Rationale?

Handsaw:
- A handsaw does the work of many knives and will outlast most
- Builds shelter quickly and efficiently
- Cuts all manner of materials -- trees, washed-up fishing nets, coconuts, green bone for the rich marrow, wet trees for kindling
- Polish one side for signalling (marginal)
- Add small cutting edges by grinding on a big, stationary rock (I have done this)
- Musical instrument for entertainment (tie me kangaroo down!)

Tent:
- A modern tent is a tarp, plus poles, groundsheet, mosquito shelter (malaria, black flies), sun/wind shelter.
- If disassembled, you still have: two waterproof tarps, poles for shelter/fishing/dip nets, fine mesh for minnows/bugs, and lots of thread/cordage

Pot:
- Very hard to improvise this simple item
- Potable water, water collection and transport, crude cooking, boiling scrap cloth for bandages, etc. etc. etc.

Matches:
- Making fire reliably without modern contrivances is pretty darn hard; just try it
- Fire solves a lot of survival problems (potable water, signalling, cleaning, disinfecting, deterring bugs/animals, morale)

Honourable mention -- I'm sad that I have to leave Wilson behind:
- Flotation device
- Water carrier
- Basket for carrying tasty, pinchy crabs
- Hat and sandals
- Lashing and bunjy cords
- Patient counsellor who listens intently to my pacing-and-planning-out-loud sessions, commiserates with my sorrows, and laughs at my inside jokes
(Sorry, Wilson, I'm sorry!)