One-hundred and sixty-four kilometres isn't a short distance, but it's not too bad.

It's a decent afternoon drive in most parts of this country, and certainly, a heck of a long bike ride.

But 164 kilometres swimming through the often stormy shark-infested waters between Cuba and Florida? Suddenly, that becomes an otherworldly hellish distance.

At the age of 61, American extreme distance swimmer Diana Nyad plans to do just that -- battling poisonous jellyfish, dehydration, delirium and the elements on a swim that will take at least 60 hours.

Only one person before her -- Australian Susie Maroney – has made the Cuba to Key West swim, but that was inside a shark tank.

Instead, Nyad will be surrounded by a team of kayakers and divers, who will carry special electronic shark repellent devices to keep the creatures at bay. To her, a shark tank is an asterisk.

It's the second attempt for Nyad, a former commentator at NPR, to swim the Cuba to Florida route. But the last try was in 1978, practically a lifetime ago when she was considered the best distance swimmer in the world.

During that attempt, a mere 42 hours, she lost 30 pounds before the swim was scuttled by bad weather.

But the weather and the sharks and the poisonous jellyfish are the not the greatest challenge for the swimmer this time – it's her own mind.

The monotony of distance swimming, perfectly-executed stroke after perfectly-executed stroke into endless, lonely saltwater, can make even the most mentally-agile person lose their sanity in a hurry.

On a previous long-distance swim Nyad has hallucinated, seeing swarms of invisible seagulls attack her. Her handlers pretended to shoo them away, rather than try to convince her they weren't real.

She's developed a method to try to keep her mind from going to dark places, by singing to herself.

If it has lyrics, it does the trick. "Itsy Bitsy Spider." "The Beverly Hillbillies" theme song. Anything by Bob Dylan.

She's been training for this. Nine-hour swims are the short ones. Twenty-four hour swims are a little less short.

During the 60 or so hours, from Cuba to Florida, she won't touch land or even a boat. Every hour and a half, she'll stop for some fuel, water, an electrolyte drink, maybe a banana with peanut butter.

Nyad and her team, all 22 members of it, are just waiting to go. She needs the sea to be quiet and warm. A change of just a few degrees can mean the difference between freezing and victory.

At 29, Nyad set the record for the longest ocean swim at 163 kilometres. That record still stands.

Now at 61, she's only competing with herself.

And the sharks. And the jellyfish. And the weather. And the insanity.