LAHAINA, Hawaii — Living in Hawaii, I often take for granted the year-round sunny weather, stunning scenery and the oversized visitors who travel thousands of miles across the ocean every winter to relax, swim and mate.

So recently, I grabbed my binoculars and headed out in hopes of catching a glimpse of these blubbery specimens in action. And I'm not talking about tourists.

An estimated 4,000 to 5,000 humpback whales — about two-thirds of the North Pacific stock — leave their frigid feeding grounds off Alaska to spend winter months in the warm Hawaiian waters every year to breed and calve. Although they can be spotted from the shores of every Hawaiian island, taking a whale-watching boat tour from Maui gave me an up-close look and a true appreciation of these massive mammals.

The hub of humpback activity in Hawaii is in the shallow, temperate waters in the channels between the western coast of Maui and the island of Lanai and the small island of Kahoolawe.

There are dozens of whale-watching tours to choose from. I went with the Pacific Whale Foundation's Eco-Adventures, which has 15 daily cruises from two Maui harbors. Like other operators, they guarantee a whale-sighting or you get to take another cruise free.

My two-hour voyage began at Lahaina Harbor aboard the 65-foot Ocean Quest, a double-deck, open-air catamaran. I scrambled with the rest of the crowd for one of the prime seats on the top deck. But it really didn't matter where we sat, because everyone was soon on their feet.

As we chugged out to sea, the friendly and knowledgeable crew gave us details about humpback whales (which, although their numbers are slowly increasing, remain an endangered species). The females are slightly larger than the males, and the whales can grow up to 45 feet in length and weigh more than 40 tons.

Graceful giants

Within the first 20 minutes of our tour, we saw a pod of whales spouting in the distance, shooting mist into the air. It reminded me of a geyser or the Halona Blow Hole on Oahu where water shoots through a lava tube into the air.

Our guide told us humpback whales usually take a breath about every 10 to 15 minutes, but can remain submerged for as long as 50 minutes.

Grown men and women were instantly transformed into 7-year-olds as they excitedly scurried to the boat's port side jostling for position. With school in session, there were only a couple of real kids onboard.

"Oooohhh," everyone said in unison.

Another small pod appeared a couple hundred yards behind us and to the starboard side as passengers started shifting around, pointing and clicking their cameras.

It's hard not to be impressed, watching these giant mammals as they party in the Pacific. They poke their bumpy, torpedo-shaped heads out of the water, roll around, and slap their long flippers, which resemble airplane wings.

REED SAXON / AP Visitors train eyes, binoculars and cameras on whales cavorting. The whale-watching boat is operated by the Pacific Whale Foundation off Maui, Hawaii.

They're called humpbacks because when they prepare for a deep dive, they bend their backs, point their noses down and gracefully raise their tail flukes above water. The arching of their backs gives the whales a humpback appearance.

Humpbacks are mostly black or dark gray and have white markings on their sides, underside and tail fluke. They all looked similar to me, except some were big and others were bigger. They are the fifth-largest of the great whales. The unique markings on their tail flukes are like human fingerprints and can be used to identify them.

You think your kid eats a lot? Humpback calves, which weigh about 3,000 pounds at birth, consume about 100 to 130 gallons of milk per day. The milk is highly concentrated in fat.

A big splash

Whale season in Hawaii generally runs from December through mid-May, with the peak season occurring from January and February and sometimes into March. The humpbacks come from Alaska, taking a little over a month to get to Hawaii.

Skipper Mike Estes, of Juneau, Alaska, who also apparently heads south for the winter, navigated us around the waters and seemed to have a natural knack for knowing where the whales hang out. He would turn off the engine every time we neared some whales.

A federal law requires watercraft to stay 100 yards away from humpback whales, but it's all right when whales swim closer. And they sometimes did.

As we slowly made our way back to Lahaina, we found a couple of whales jumping out of the water, what's called "breaching." Talk about a belly flop. These giants lunge into the air, twist and come crashing down, creating a major splash. They continued for 15 minutes, providing us with a spectacular show.

The passengers cheered with every jump. The bigger the splash, the louder the cheers.

Cashing in on whales

In some ways, humpbacks are like the seriously wealthy, tracking the sun to the world's playgrounds. The phenomenon hasn't escaped the Hawaiian travel industry, which thrives when the humpback whales come to town. Once hunted and killed in vast numbers, whales are now the star performers of the seas. Nearly 100 countries have burgeoning whale-watching industries; only a handful of nations still allow their slaughter.

Maui, a onetime whaling capital, is now a whale-watching capital, drawing nearly 900,000 tourists during the December-May humpback-whale season. Many visitors arrive with whale watching at the top of their wish list, tourism officials say. They're rarely disappointed.

Some material from the Los Angeles Times was used in this report.