After circumnavigating this massive continent for a mix of thriving cities, golden beaches, and outback outpost, you can see the highlight: a diving or snorkeling tour of the biggest reef in the world. Swim alongside tropical fish and coral, and if you're lucky you'll get a glimpse of the dugong (sea cow) or the near-extinct large green turtle.

Although you can catch glimmers of the aurora borealis in many spots in the Northern Hemisphere, it's at its most awe-inspiring along Norway's majestic coastline of glacier-formed inlets and high cliffs punctuated by waterfalls.

The rugged terrain of the 49th state harbors many icy glaciers, and this jagged stunner is among its most impressive for its sheer size — it stretches 76 miles — and translucent blue hues. Its surrounds are home to moose, brown bears, and black-tailed deer. That thunderous sound? Massive chunks of ice crashing into the bay.

History buffs delight in these colossal wonders built for pharaohs who once ruled the ancient world. An engineering marvel, their construction is still shrouded in mystery — which makes it even more of an intrigue to visit.

A cruise to the White Continent is as far-flung as it gets. The reward for braving the icy frontier: spectacular sightings of boisterous penguin breeding colonies — Adélie, emperor, gentoo, maccaroni, and chinstrap — some of them as large as a million birds.

Darwin was fascinated with this volcanic archipelago for its rare, endemic creatures not found elsewhere in the world, giant tortoises, Galápagos penguins, and fur seals among them. As it is today, it's still a living museum and a showcase for evolution.

A journey to China is a mystical immersion into an ancient culture, and nowhere is that more evident than an excursion to this famous fortification built over several millennia, originally as a defense against marauding invaders. The wall sprawls over 5,500 miles and most parts are still intact — despite the fact that some sections were bound together by glutinous rice flour.

It's not a stone's throw from the cruise port (in fact, you'll have to book a land tour departing from Lima), but at least you don't have to hike the Inca Trail. Either way, this ancient Inca citadel is worth the trip: Cloud forests surround the stone constructions tucked into the slopes, peaks, and valleys of the Andes.

The eruption of Mt. Vesuvius in 79 AD sealed the fate of this once-flourishing metropolis near Naples, where you can freely wander the haunting ruins — temples, amphitheaters, a brothel — since uncovered from pumice and volcanic ash.

 Ancient ruins may seem like a dime a dozen in the Mediterranean, but this former capital of Roman Asia Minor, a bustling trade city, is a quintessential slice of Greco-Roman life. Visit the gladiator cemetery and the magnificent Library of Celsus with its delicate columns and statues of Greek virtues.