Don Asks "When the tide is out are the inlets to the lagoon dry so as you can walk across them "easily"?"
The main inlet to the lagoon by the old village is never fully dry. At high tide it can get chest deep or deeper in places, and the current runs pretty strong between high and low tides. At low tide, there are still areas that can be about 4 ft deep, so definitely a body of water that can be crossed, although not necessarily without a shark induced adventure. If you haven't seen Mark Smith's video of crossing the channel, check it out
Mark's Shark EncounterAs for Baureke passage, it is much more shallow, and sometimes entirely dry. In 2001, it was completely dry, but was again open to the lagoon in both 2007 and 2010, and easily crossed.
From the shipwreck clockwise around to the 7 site on the beach would probably only take a couple of hours. The presumption is that after the USS Colorado's search planes flew off, eventually AE / FN would have begun to explore the rest of the island. Water would definitely be a problem. Down by the 7 site is where turtles nest, and I would think turtle eggs might be a good source of both protein and moisture.
Andrew