The spring thaw is under way as cruise ships sail north to Alaska's scenic Inside Passage for the start of another busy season next month.
Many passengers book early cruises hoping to see the magical northern lights that light up Alaska's night skies in winter. Known as the aurora borealis (Latin for northern lights), the spectacle colours the sky in vivid shades of green and red, and is sometimes seen out of season.
The bright, moving light of the aurora is created by collisions between electrically charged particles from the Sun as they enter the atmosphere. They are seen close to the Earth's magnetic poles, and colour variations are due to differences in the types of gas particles colliding.
More than 30 big cruise ships will join smaller expedition vessels in Alaskan waters this northern summer when almost one million passengers are expected, including many Australians who rate Alaska as their top cruise destination.
The latest figures from the International Cruise Council Australasia show more than 19,000 Australians took an Alaskan cruise in 2010 - an 8 per cent increase on the previous year.
Alaska is seen as America's last great frontier. It has a raw natural landscape, and characters abound in small towns where there is often a ratio of one woman to every nine men.
With no road access to many towns, a cruise along Alaska's Inside Passage is the only way to get to see one of the State's most spectacular sites, Glacier Bay National Park - other than on a sightseeing helicopter or float plane.
Awe-inspiring glaciers thaw and break into the sea in huge chunks in this pristine wilderness of soaring snow-covered peaks where bears, mountain goats and moose wander and eagles soar.
As well as whale and seal sightings, the cruise lines offer shore excursions that run from dog mushing (Alaska's official sport) to game fishing, bear viewing and sightseeing flights.
The most popular Inside Passage excursion is the steep ride on the White Pass and Yukon Route Railroad in Skagway. Holland America, Princess Cruises, Carnival, Royal Caribbean, Celebrity, Crystal Cruises, Norwegian Cruise Line, Regent Seven Seas, Oceania, Disney, and Silversea all sail Alaska's Inside Passage on itineraries from seven to 14 days, with calls into Juneau, Sitka, Ketchikan, Skagway and smaller towns.
Some cruise ships sail on to Whittier, a gateway to Anchorage, Alaska's biggest city, which is an hour's drive away, and on to Fairbanks and Denali National Park for great land touring options. This season, Holland America's Amsterdam sails on to Anchorage's main port, only five minutes from downtown, for 17 hours of shore time.
Princess Cruises, one of the biggest cruise operators in Alaska, has seven ships sailing seven itineraries this season, including weekly cruises between Anchorage and Vancouver via the Inside Passage. It also offers a mix of land and sea holidays that take in Glacier Bay and Denali national parks on its cruise ships, Princess Rail and Princess-owned wilderness lodges.
Another new offering combines five days aboard the award-winning Rocky Mountaineer that takes in the breathtaking Canadian Rockies by rail, with a seven-night cruise on a Holland America ship from Vancouver.
- *Tips for cruising in Alaska * *
·If time is limited, fly into the capital of Juneau, in the Inside Passage, to board a seven-day voyage. Most cruise ships sail from Seattle, Vancouver, and San Francisco, which adds extra cruising days to the itinerary.
·Alaska is often known as the land of the Midnight Sun, and with so many daylight hours, it is well worth the added expense of booking a balcony cabin to view spectacular scenery from dawn until dusk.
·Pack layered clothing. There will be sunny days as well as others that are decidedly chilly.
·Book early for excursions that appeal because some are so popular that they sell out fast.
·Shop for Native American art and craft unique to the region.