OFF THE COAST OF NEWFOUNDLAND -- The icebergs may be big, but the ocean is endless.

And so the hours pass as Tristan Krein stares out the window of the Hercules C-130, searching for ice. Sometimes, he takes out his binoculars and scans the empty horizon; other times, clouds obscure the waves and he is a man looking at nothing.

"Sometimes, we're begging for things to look at," says Krein, 35.

But sometimes, the members of the International Ice Patrol look down and they see peaks of glistening white, floating in the frigid currents. They record the iceberg's location, its size and its shape, and they know that every observation they make is crucial.

Every other week during the iceberg season -- usually, from February to July -- the Ice Patrol flies over the North Atlantic, keeping track especially of the southernmost area in which icebergs have been spotted. This is key; the patrol's findings tell mariners how far south they must sail to avoid any chance of hitting an iceberg.

These, after all, are the waters that claimed the RMS Titanic.

A perfect record

Indeed, the Ice Patrol, operated by the U.S. Coast Guard on behalf of 17 countries, has been looking for icebergs since 1913, when a horrified world resolved that it would never again allow the kind of accident that sent the Titanic to the Atlantic's floor.

In all those years, there has not been a single reported loss of life or property from a collision with an iceberg in an area the Ice Patrol proclaimed to be safe.

"It's incredibly important," says the patrol's commander, Bob Desh.

It's obscure, as well. There have been books written about the patrol -- in fact, Krein remembers reading one when he was in grade school -- but mostly, it does its work quietly.

Krein did not join the Ice Patrol because of that children's book. He, like his fellow "ice picks," joined the patrol because it's a small unit with a unique mission.

"It was different from everything else," says Bryan Grebe, 26. Like the others, he is a marine science technician. Chances are, if he wasn't a member of the ice patrol he would be inspecting vessels to ensure they are safe.

Instead, they supervise as temperature and current sensors are dropped from the huge cargo plane. They stare out the windows, or they watch over the shoulders of technicians -- "tweets" -- who monitor forward- and side-looking radar.

Plugged into computer

And at the end of a day aloft, they examine their data and send it to patrol headquarters in Groton, Conn. There, it is plugged into computer models that will project the drift of the icebergs; twice a day, the patrol issues reports that are dispatched to the nations that share in the $11,000-an-hour cost of the patrol's flights.

The icebergs calve from Greenland's glaciers, the result of thousands of years of accumulated snow. They are carried south to the Grand Banks by the Labrador Current. Four hundred to 800 make it as far as the 48th parallel, which is even with St. John's, Newfoundland. Eventually, they melt in warmer waters.

The smallest ones are known as growlers, because they make a growling noise as they rise and fall with the ocean swells. The portion above water -- the smallest part -- is less than 3 feet high and less than 16 feet long.

The largest iceberg ever seen in the North Atlantic was 550 feet tall, nearly as tall as the Washington monument. But most are small or medium-sized, like the one that destroyed the Titanic -- 50 to 100 feet high and 200 to 400 feet long.

About 70 percent of the time, Desh says, they don't see the icebergs at all -- they're obscured by clouds or fog, and are only observed by radar.

Mostly boring work

So this is the Ice Patrol's glamorous duty: six to eight hours in a cold, noisy (earplugs required), 29-year-old tin can of an airplane, with the likelihood of seeing nothing.

Sometimes, a flight crew member will set up a hammock back in the plane and sack out.

Climb up on the flight deck and you'll find flight engineer Chris Collins paging through a book filled with compact discs -- Veruca Salt, George Thorogood, Rush, Shania Twain. He pops one into a CD player connected to the intercom system. "That's our flight entertainment," he says.

Pilot Carey Hixson and co-pilot Wes Hester often have their feet up. The plane must fly precise routes so that its radar will map the seas precisely, and autopilot does that.

"Takeoff and landing -- otherwise, it's boring," says Hixson.

So why do they do it?

Partly, it's the pay -- a $70 per diem while they're in Newfoundland, and $150 per month in flight pay.

But mostly they do it because they feel they are accomplishing something important.

They know what happens when ice meets metal. Every year, they mark the anniversary of the Titanic's sinking with a ceremony outlined in the Coast Guard's manual of standard operating procedure.

On this year's 90th anniversary, on April 15, the C-130 dipped to 400 feet, affording the crew a remarkable view of two icebergs, one of them about the size of the one the Titanic hit.

And then crew members dropped two bouquets from the open cargo door.

"It puts a lump in my throat," says Jim Wineteer, 32, one of the tweets.