The cry came from a passenger as we were being briefed on Antarctic protocol and conservation.

“Iceberg!”

All 190 guests on the Explorer II rushed to the starboard side of the ship to witness the giant berg, white with distinct horizontal stripes of cobalt blue and turquoise, that seemed to be the size of several city blocks. Close by was a much smaller iceberg, sculpted by the wind and waves and covered with more than a dozen penguins.

At the stern of the ship, several albatrosses floated lazily along. In the distance, close to the jagged mountain peaks of Elephant Island, with its wide glaciers running to the sea, two fin whales surfaced every few moments to blow spray.

Nature presented a spectacular show upon our introduction to Antarctica, an increasingly popular destination for adventure-minded travelers keen to interact with wildlife and view spectacular scenery untouched by humans.

Over the next few days we explored a part of the world that, in the words of one seasoned traveler, “is the closest I’ve ever come to visiting another planet.”

Explorer II passengers are treated to the sight of a colony of gentoo penguins.

On average, Antarctica is the driest, the coldest and the windiest continent on earth. It’s also the continent that holds 90 percent of the ice and 70 percent of the fresh water on the planet. During the summer months, most of the beaches, covered with penguins and seals, are more crowded than any in Cape Cod.

Our home base for this 11-day eco-cruise was the Explorer II, a 10-year-old luxury expedition ship with a reinforced hull, leased for two trips a season by the upscale Regent Seven Seas Cruises. The normal capacity of the ship is 300 passengers, but Regent keeps its Antarctic numbers to fewer than 200.

Unlike the early explorers, we could marvel at the surroundings, then retreat to gourmet meals and fine wines, comfortable staterooms, a huge library and attentive service by a caring crew. Fourteen countries were represented among the passengers, but most were from the United States.

Many cruise ships now sail around the bottom of South America, skirting the Antarctic islands and mainland without allowing passengers to leave the ship. Explorer II, with its limited passenger load, is allowed by international agreement to anchor almost anywhere and take visitors on its fleet of 12 zodiacs for intimate interactions with the land, the ice and the wildlife.

Key to the success of Explorer II was its team of 14 expert naturalists and scientists who guided the zodiacs on our twice-daily trips and gave illustrated briefings about the wildlife, geology and politics of this vast mushroom cap at the bottom of the world.

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First stop, on an overcast but pleasant day (about 45 degrees — 7° C), was Half Moon Island, part of the South Shetlands. Landing the zodiacs and putting our feet on Antarctic territory for the first time was memorable. Not only were we greeted by fur seals lazily guarding the pebbly beach, but more than 3,000 pairs of noisy chinstrap penguins watched us curiously or hopped and walked, Charlie Chaplin style, toward the water or on the rocky slopes.

We were warned not to approach the penguins any closer than 15 feet, but, as we stood still, many of the more curious birds decided to inspect us and waddled over for a closer look.

In the afternoon, en route to the active volcano on Deception Island, we came upon four humpback whales, a common sight, since up to 80 percent of the world’s blue whales come to Antarctica to feed. Our Italian captain slowed down so we could observe the quartet of giant mammals devouring swarms of krill. These small, shrimplike crustaceans are in abundance during the Antarctic summer, and form the basis of the whole food chain.