Portland is kind of a pit, of course, Navy yard, dusty little ole city, but you will be within an hour or 2 of all kinds of nifty wilderness, historical attractions, rocky coastline and just a jump to Boston and another to the beaches on Cape Cod.
If you have never lived in New England it will be like a roast chicken when you start exploring, you will turn up all this little tidbits everywhere you go.
For your whitewater you will want to head inland to Vermont and New Hampshire, both not real far away.
Best of the beach and the mountains within spittin distance, that about sums it up.

