Native Inuits called them pikaluyaks. They were monstrous to their ancestors 4,000 years ago and they are monstrous today, as tall as the Empire State Building, larger than a city block and a menace to North Atlantic sea lanes.

They are icebergs, and their main source is Greenland.

Sailing amid these incredible mountains of ice is one of the unusual thrills abroad a new cruise line that seeks out these silent and gargantuan sentinels.

The axiom that if you've seen one iceberg you've seem them all is just not true. They come in all sizes, shapes and colors -- blues, greens, browns, black, clear, and, of course, white. Most awesome of all is what you don't see, because only one-seventh of the frozen leviathans is above water.

Dotting huge, heart-shaped Disko Bay on Greenland's west coast, they make Alaska's Glacier Bay look like a home ice bucket.

But icebergs are not the only thing to see while on a cruise to this different destination. Taking full advantage of the short summer and the 24-hour midnight sun, Greenland cruise passengers (50 at a time aboard the 500-ton Nordbrise) also visit quaint villages such as Jakobshavn, with 3,500 residents and 5,000 dogs; identify more than 50 species of birds (many rare), although the island has no trees; and view the stark beauty of massive ice and rock in one of the most pollution-free areas of the world.

Modern explorers, in living-room comfort, follow in the footsteps of great explorers who less than 100 years ago all left their mark on conquests of the great island, including American Robert Peary, German Alfred Wegener, French Paul Vistor, Norwegian Fridtjof Nansen and Danes Knud Rasmussen and Lauge Koch. It was then and still is called the "Land of the Explorers."

Greenland is the world's largest island, more than three times the size of Texas. An icecap, with depths up to 8,000 feet, covers all except a small percentage of land along the coastal fringe. On this narrow strip, against incredible odds, Inuits have managed to exist for four centuries.

These native-born Greenlanders, estimated to be 40,000 of the population of 50,000, are described as "having one foot in the Stone Age and the other in the 21st century." One might be harpooning a seal in the morning and riding in a Mercedes taxi in the afternoon.

The Nordbrise sails in Greenland every summer, between mid-June and the end of August. (Surprisingly, summer on this northern island can be most pleasant, with a mean temperature around 50 degrees, but unpredictably changeable.)

Getting there is not necessarily half the fun, even though Eastern Airlines, Nordair, First Air and Greenland Air have coordinated their schedules to make the traveler's trip to and from Montreal as easy as possible. But it is more than 2,000 miles through two time zones from the Canadian city by air to the Nordbrise dock at Jakobshavn, with the final leg across the Arctic Circle made by helicopter. (Included in the cruise price are nights at the airport Hilton International in Montreal and Greenland Hotel in the capital city of Godthab.)

The week-long cruise calls on villages and islands around weather-protected Disko Bay (named by Dutch whalers who described the bay as being in the shape of a disc). It includes visits to a shrimp factory at Christianshab, towering bird cliffs and calving glaciers in Torrsukatak Fiord, the preserved but deserted coal-mining village of Qutdligssat, museums, the Ionosphere weather station and scientific Arctic Station at Godhavn and, the cruise highlight, a visit to Jakobshavn, with its spectacular iceberg-filled fiord.

Visitors see illulissat (ice mountains) on a visit to Seremeruit, with native settlement ruins dating to 2000 B.C. From this promontory you have a commanding view of Jakobshavn fiord, into which the world's largest glacier pours 16 million tons of ice each day.

In fact, all the statistics about this glacier are staggering. It is 30 miles long, with a width of four to eight miles. Icebergs don't calve or fall off this glacier -- which is how most icebergs are formed; they are forced off the glacier by tidal and water pressure from the bottom. In this manner a new iceberg is created every five minutes and floats into Disco Bay.

As spectacular as the bergs are to visitors, occasionally the fissure-like harbor at Jakobshavn has to use a small but powerful boat called an ice mule to push unwanted ice out of the ship channel. If your ship makes its overnight stop at the right time, you may see these ice mules at work in the tiny fishing village. A must for visitors is lunch at the Hotel Hvinde Falk with Mattek suppe, Krebs kold i dill, Rensdyr boef and Tuborg (whale-skin soup, lobster-type crustaceans, reindeer steak and Danish beer). The cost is about $15 per person.

The Nordbrise is immaculate. Built as the Rost in 1959 for Norwegian coastal service, it was renovated in 1983 when its name was changed and it became a cruise ship. Today, the Nordbrise docks every night, offering comfort to its passengers with an attentive crew of 13 and shipboard amenities that include a large sauna; a booth-filled, one-sitting dining room; comfortable cabins and a variety of food.

Veteran Arctic Capt. Gunther Leling is aided by cruise manager Paul Christensen. Shore excursions are made by a large inflated rubber boat, and local tourist organizations are most helpful in the villages.

Cabins are well-ventilated, newly appointed and decorated, all with private facilities and plenty of closet space. There is a choice of single, bunk or double beds. (Note: Cabins with portholes are worth the extra money ($200-$300) because of the bay view.)

To the Greenlander, Greenland is Kalaallit Nunaat or "people's land," and Quqertassasug, meaning "big island." Except for the icebergs, visitors will probably best remember that this huge island is, indeed, green -- even though the color comes from only a thin fringe of arctic grasses. But Greenland is not without its problems of trash, unemployment, alcoholism and the pains of transition to the modern world: A neighbor visiting by dog sled can join his hosts in hating J.R., who arrives by cable television.