Rivers are rivers and the sea is the sea, but sometimes one acts like the other.

So it is at Bethany and all along the coast at salt-water inlets where the sea and the bays meet in a fast-water rush. The river near Bethany is the Indian, which isn't a river as far as I know, but looks like one when the tide's running.

We went to Indian River Inlet by boat at what was supposed to be the end of flood tide, but the tide table was wrong. Instead, it was the first of ebb. "Where you been?" asked the man at the bait shop, "Under a rock?"

The foul-up skewed our fishing -- we were aiming to hit the last of flood and the first of ebb, the best time for flounder.

When the Indian River turns itself around, the underwater world lights up. Divers say that when the tide quits and things are calm below for that hour of change, they can watch the flounder and other bottom-feeders lift off the bottom to go foraging.

When the next tide-surge starts the water the other way, it washes out shoals of bait that were hanging in the slack water, starting a feeding binge among the predators.

But we'd missed the change, so we headed out to the ocean where tidal current is dispersed and has less effect on the fishing.

If you go through the inlet when the tide is ripping, as we did, you might as well be in a whitewater canoe. All of Indian River Bay and Rehoboth Bay, responding to the pull of the moon, is trying to get out into the Atlantic, rushing through a cut a hundred yards wide.

There were whorls and standing waves, tide rips and whirlpools, just like in a big river. An aluminum runabout came crashing in against the current, hit a wave, corkscrewed straight up and landed on its feet.

Only the top two feet of the six-foot-tall black can marking the channel was visible, the rest sucked under by the rampaging tide.

It reminded me of Hellgate at the northern end of New York's East River where the river connects the Atlantic Ocean with Long Island Sound. It's aptly named for the hellacious tides that ebb and flow between the two great bodies of water every six hours.

Once, in a 52-foot sloop with the engine open wide and the sails up and drawing, we were barely able to make headway against the tide coming through Hellgate. Slack tide is when you want to run that stretch. Against the current is second option -- then you at least have some control. But watch out for those wild and wonderful New York kids throwing rocks from the beach.

The worst option is with the tide, when the current shoves you along at six or seven knots and you must generate at least two knots on your own to keep steerage. So you end up careering through at breakneck speed, as out of control as the city you're shooting past.

Anyway, back to Bethany where we rode the current safely out of Indian River and caught a few flounder in the ocean. I was thinking about the wild river to the east. Another 50 miles and we'd hit the Gulf Stream, the river within the sea that runs north from the Gulf of Mexico clear across the Atlantic and up past the British Isles.

When you hit the western edge of the Stream you know it. The water turns from the gray-green that marks inshore waters to brilliant clear blue. That's where the marlin roam, slashing at bait with their long bills.

The line that marks the Gulf Stream is as clear as though the Highway Department painted it there, though of course it moves every day, in or out. When you're there, you know it. Not so on the east side of the stream where, buffeted by countercurrents and weather, the stream breaks up into an undefinable edge. That's what it says in the books; I haven't seen that side.

We fished for a while and turned back in when the tide was still ebbing. At the mouth of the inlet you could see the edge of the tide current where the water was roiled and sandy, creating an edge as clearly defined as the Gulf Stream's and a good place to fish, because the predators would hang there, picking off bait washed out by the tide.

In an hour we caught two bluefish, a sea trout, a small shark and the biggest flounder we'd caught all day.

Then the tide quit, the fishing slowed and we went home through an inlet as placid as a millpond.