It's going to be hard to find one knife to do all that. That's just the nature of blade steels: Spyderco makes fixed blades and folders out of H1 steel that flat out won't rust in salt water and would make great dive knives, but you might be disapointed with one of those if you try to chop hard wood with it. Likewise, a good chopping steel (which would probably be some type of carbon steel) is going to rust in salt water.
Ask anyone here, and I'll bet they will tell you: the first knife they bought thinking it would make a great all around survival knife probably got replaced by another knife once they learned, through experience, what they really needed out of a knife. You'll only learn by doing. For this reason, I advise you not to go out and pay hundreds and hundreds of dollars on a high-end production knife or a custom knife. Buy a couple or several good-quality but affordable knives and try out a bunch of different steels, blade styles, and manufacturers, and then after some in-the-field use, you'll learn what works best for you and you can tell a custom maker what you need in a design.
My personal favorites are the Becker Knife and Tool line being produced by Ka-Bar. You can get a BK2 from them for around 60 bucks, and it will do a lot of what you say you need a knife to do. I would argue that this is probably one of, if not the, best all around outdoor knife for that price point. It won't, however, be a good knife to dive with because it will rust. As I mentioned above, a Spyderco fixed blade in H1 steel would be an ideal dive knife, simply because it won't rust. I own one of their folding knives in H1 steel and have swam in salt water several times and have done nothing to the knife afterward and have had no rust. Granted, it won't slice as well as some other stainless steels, but it is truly stainless. Why the heck Spyderco does not make a neck knife out of H1 is beyond me, but that's a bit off topic.
Something else to note: very few experienced outdoorsman are going to go into the wilderness with just one knife on them, so you don't have to expect one knife to excel both at battoning through hard woods and fileting a salmon. You'll be better off with one large chopper with an edge around 7 to 9 inches in whichever type of carbon steel you prefer and then a smaller one in whichever stainless steel you prefer for more precise cutting tasks.
