Penny Palfrey's attempt to conquer the only Hawaiian channel not crossed by a swimmer — the 75 miles between Oahu and Kauai — was cut short by a wall of Portuguese Man-o-War.

Palfrey, a 47-year-old grandmother from Australia, got about halfway but her final hour of swimming was marked by the searing pain of stings all over her body.

She started at 8:08 a.m. Saturday about a mile south of Kaena Point and ran into the tiny jellyfish about dusk. She continued for another hour, not wanting to quit, but was forced to stop at 8:10 p.m.

Palfrey had covered about 38 miles in 12 hours and 2 minutes. Until the stings, she was swimming with such strength that her escort crew felt she would finish well under the 30 to 40 hours originally predicted.

Swimming across the Kaieiewaho Channel had only been attempted once, by Jonathan Ezer in 1975. Ezer, a Kalani High School graduate who lives in Texas, had only done one other marathon swim, crossing the 26-mile Kaiwi Channel between Molokai and Oahu in record time in 1974.

That record was broken Saturday by Palfrey's husband, Chris.