MATTINGLY GLOBAL

On a personal island, one can decide for himself how much he wants to interact with other navigators. There would have to be at least one (brick and concrete) building with a spacious cellar on the island however, to provide shelter in case of a hurricane or some other emergency. (comfortably) survive a full-blown global nuclear, chemical, and/or biological conflict.
The configuration of your ocean-based habitat. Will it for example be a concrete island, and if so will it be fixed to the ocean floor (on pillars), floating (with heavy, fixed anchors to keep it in place) or a combination of the two? Other possibilities include underwater habitats, living on a large(r) ship, which could either be some used hotel barge, a modified container ship, tanker or trawler, or, ideally, a small/medium-sized cruise ship.One Island option would be constructed from floating or fixed concrete structures moored/built atop some shallow spot like a sand bank, rock formation, or coral reef. Alternatively, one or several large, soil-filled "scrap" ships could be moored or ran aground in a suitable location, thus forming an instant "village" which could later be expanded with other vessels and structures. (Please see “WEST CONTINUES TO SEND "TOXIC" SHIPS TO INDIA” an article put out by Greenpeace in 1999. The coast of India became a haven for once toxic ships that have been naturally cleaned over time.) Artificial "electric" reefs could be used to gradually cement everything together until a "real" island is formed.

A fixed platform offers great stability, eliminating sea-sickness unlike on a ship or other free-floating structure, it has more of a real "island" feel to it, can support heavier structures, and will not easily sink. However, inherent to the fixed platform is of course lack of mobility and the possibility that a rigid platform could be more vulnerable to bad weather than a flexible one, though this depends on the specific design. The rising of the sea level (due to global warming) can be combated by simply add a couple of extra meters to the base level of the structure.

The floating concrete platform allows for mobility - one can choose from a much wider variety of locations then with a fixed platform, and move around if necessary. The stability of a concrete island would probably be much better than that of a ship, although the action of the waves could still be felt. You could relatively easily add on new structures, both horizontally and vertically; the island could really grow. A risk could be the floating platform could at least theoretically sink if damaged badly enough during a storm, attack, or as a result of fundamental design flaws / structural weaknesses. Also it could carry less superstructure, soil etc., and the wave action could cause discomfort to some inhabitants, as well as displacement of any non-attached objects during rough seas.Another option would be to take over "second hand" (but still seaworthy) ships, and use them as a mobile base of sorts; roaming international waters. Stealth, mobility, obscurity, and release from the global land-constitution give practical autonomy.Barges are much easier to maintain than a ship because there are no engines and related equipment, just a steel hull with some kind of (possibly prefabricated) superstructure to live in. In this configuration, it's basically an old “house-boat” on steroids. By linking several barges together you can have a small town, complete with greenhouses for growing fruits & vegetables, a small park, a swimming pool etc. If you want to move around you can hire a tug, or (preferably) use your own. The navigator will want to moor it in a relatively quiet spot out of the way of tornadoes and such -- in a circular atoll's lagoon, for example. Mobility-wise a barge ranks somewhere between a ship and a floating concrete structure. It could be useful as a base, but having at least one medium-sized, seaworthy ship for supply, transportation, and emergency evacuation is more or less essential.