Five extreme Cape Town swimmers are set to put their icy water experience to the ultimate test by participating in one of the world's longest cold water swim races around a remote island off Alaska on August 16 — wearing only their costumes.

Most of the approximately 50 solo and relay participants in the Pennock Island Challenge, in south western Alaska, will don wetsuits and swimming caps when they race 13.2 kilometres in water temperatures between 12 and 13 degrees — similar to ocean temperatures off the Atlantic Seaboard.

The five Capetonians will, however, be among only 11 swimmers not wearing wetsuits.

In addition, at least three of the five will be the only participants to forgo swimming caps which retain body heat as part of their ongoing attempts to "push the envelope", said one of them, Ram Barkai.

Barkai (51), will be accompanied by Andrew Chin (40), Kieron Palframan (35), Ryan Stramrood (35), and Toks Viviers, (47).

Barkai holds the Guinness World Record for the most southerly swim in Antarctica while Chin recently undertook an icy swim in Lake Zurich in mid-winter with Barkai.

Stramrood and Palframan have both completed the "Everest" of long distance swimming — the English Channel, while Viviers has completed the challenging Robben Island crossing several times.

The five are all seasoned cold water athletes and annual participants in the extreme Cadiz Freedom Swim from Robben Island to Blouberg but this will be the longest period — about 4.5 hours — they will have spent in temperatures as low as 12-13 degrees.

"None of us has ever swum this distance in these temperatures, so it will be a totally new challenge," said Barkai, adding: "This is almost as far as a double Robben Island crossing — regarded as one of the world's toughest cold water swims — at a similar temperature," he added.

After completing the Alaskan challenge, the five will travel to San Francisco where they intend to swim across the bay to Alcatraz and possibly participate in the annual 10km Bay to Bridge swim race. They will then undertake a long distance swim in the ocean off San Diego before returning home on August 25.

Sapa