Every river makes music, but each one sings a slightly different song, and all rivers change their tune from time to time. That's why pre-trip scouting is such a good idea. Surprises may make for good birthday parties, but they're no fun at all on the water.

Ready? Then let's head down the trail and see what we can see. Here's an osprey-eye view of what lies ahead. We'll start in Section #1.

How about that! The water level's no higher than it was last time — not quite bankfull. Notice how much bigger the river is below the junction with the outlet, though. Each tributary pours more water into the main channel. Waves are higher, eddies are more powerful, and mistakes are more costly. On this river, at this water level, the whitewater begins in earnest just downstream. See the big rocks poking up above the surface? Water sluices past them on either side, and good-sized eddies form below each one. Slalom city! But what about the rocks you can't see? They're the ones hidden below the torrent. From upstream, your only clue to their presence will be a hump in the water — the "pillow." But these pillows aren't stuffed with feathers or foam. They're filled with rocks. And if that doesn't keep you awake, nothing will.

Pillows usually don't look particularly threatening, but you won't want to get too close to them. It's easy to hang up on the submerged rock, and things will start happening very fast after that. A broach is always a possibility, followed almost immediately by a cold swim. Even if you manage to scrape over — and slippery plastic boats do a much better job of this than aluminum canoes — the reaction wave just downstream of the pillow can still dump you. All and all, pillows are best appreciated at a distance. In fact, when you're scouting a run, it's usually a good idea to plan a route that skirts close to the rocks you can see.

Sound crazy? It's not. (At least it's not if you have a good repertoire of boat control strokes, and if you're running a river that's otherwise within your abilities.) The eddy below each visible rock is an island of comparatively quiet water. In slow-moving streams eddies are barely-noticeable slicks. In whitewater rivers, on the other hand, they're often more or less turbulent pools with pronounced upstream flow, guarded by a wavering boundary of conflicting currents and marked by a noticeable drop or "step." This eddy-line can be a trap for the unwary novice, of course, but the calmer water on the other side is a gift to more experienced paddlers. An eddy can provide a safe harbor in the middle of a maelstrom. It's a good place to bail, to catch your breath, and to scout the next drop ahead.

Eddies are also good places to hone your whitewater skills, and playing the river often means executing a series of eddy-turns, one after another. Catch an eddy on one side, peel out on the other, then head downriver to the next. There's no better way to learn to read the music of a river.

We're scouting from shore today, though. And it's time to move on. Look downstream. See where the river drops sharply? Lively, eh? Now check out that really BIG pillow in mid-channel. Must be one hell of a rock under there! And it seems like the whole river's pouring over it. Just look at that…well, what is it, anyway? Sort of like a hole in the river, isn't it?

Right. A hole in the river. A "souse hole." Think mega-pillow joined to super eddy. No friendly sentinel rock visible upstream. Just a lot of water washing over a hidden boulder. And then a hole. The river's flowing into it from all sides, too. There no refuge in this eddy! Only turbulent water, water with so much air in it that it won't float a boat or give a paddle any purchase.

That's not all, either. The reaction wave at the downstream end of the hole isn't just steep — it curls back and breaks upriver. So if you drop into the hole and somehow manage to stay afloat, you've still got to climb a breaking wave to get out. That's not an easy job, and it's no wonder that these waves are known as "keepers" or "stoppers." Call it truth in advertising. Holes are no place for open canoes, unless those canoes are filled with float bags and paddled by experts. Even kayakers will find they need to think in three dimensions to stay in control. It's a job for the submariners among whitewater paddlers. Playing holes is definitely not a game for novices.

Let's move along. There's a bend just ahead (see Section #2 on the map). But what's this? A new trail swings away from the river and heads off into the woods. A portage trail? Seems likely. Maybe we ought to take a closer look at that bend in the river.

Hmm. Doesn't look too good, does it? The current's running strong here, and that rocky ledge on the right — river directions are always given from the perspective of a paddler looking downstream — funnels all the water toward the outside of the bend. There's a well-defined chute, though. If the river ran straight it would be a good bet: a classic downstream-pointing V.

But the river isn't running straight, is it? And high water is no time to take chances on the outside of a bend. That's not the only problem, either. Just look at those big waves downriver, the ones that begin at the bottom of the chute, past the rock ledge, where the channel widens again and the river slows down. See how the water piles up? It's a chaotic scene. One towering wave follows another in what looks like an endless procession. But wait a minute — there's order in the chaos. The individual waves surge and slump from one minute to the next, but they always stay put. That's why they're called "standing waves." And did you notice how the first two waves in the series are curling back upriver? Just like the keeper in the souse hole we saw earlier.

Now we know what the portage trail is for. But we're not through yet. There's a crowded rock-garden below the standing waves. Each upstream-pointing V marks a rock, and there are a lot of upstream-pointing Vs. It'd be a fun run in an empty boat, but if you'd taken on water in the standing waves.… Swim time for sure. Still, it wouldn't be hard to lift over the ledge and skirt the worst of the standing waves, would it? Then the rock garden would be a piece of cake. But the portage trail is taking its time getting back to the river, isn't it? Do you think there's something else ahead? Let's scout a little farther (see Section #3 on the map).

Aha! So that's it! Look downstream again. What do you see? A nice, clean horizontal line cutting across the river. And listen. Can you hear the new bass note in the water's music? Unless I miss my guess, there's a falls ahead. No wonder the portage trail hasn't returned to the river yet.