Tip of the iceberg: my 3,000-mile journey around wild Alaska, the last great American frontier

In 1899, railroad magnate Edward H. Harriman organised a most unusual summer voyage to the wilds of Alaska: He converted a steamship into a luxury 'floating university,' populated by some of America's best and brightest scientists and writers, including the anti-capitalist eco-prophet John Muir.

Those aboard encountered a land of immeasurable beauty and impending environmental calamity.

More than a hundred years later, Alaska is still America's most sublime wilderness, both the lure that draws a million tourists annually on Inside Passage cruises and a natural resources larder waiting to be raided.

As ever, it remains a magnet for weirdos and dreamers.