HAVANA – Endurance athlete Diana Nyad forged ahead through the Straits of Florida with renewed vigor Sunday in pursuit of a record 103-mile unassisted swim in open waters without the aid of a shark cage.

The 62-year-old Los Angeles woman was said to be comfortable, confident and steady at around 50 strokes per minute after a harrowing night of painful jellyfish encounters — despite an improved bodysuit.

Nyad was stung four times during the night, on the neck, lips, hand and forehead, according to some in her 50-member crew who updated fans through social media.

“Today is more like swimming,” one quoted her as saying, via Twitter. “I don’t know what you would call last night … probably surviving.”

Sunday evening, about 26 hours into the swim, Nyad had traveled about 27.7 miles and was taking advantage of “ideal conditions,” with calm seas and little wind.

Video posted on her website showed her on a break joking with the crew and sucking nourishment from a long tube.

“I’m sort of cruising a little bit right now. I feel like pushing it. I have the energy but I’m saving (it),” Nyad said.

Nyad had planned to don the bodysuit, which covers her from head to toe except for holes for the eyes, nose and mouth, at night, when jellyfish tend to rise to the surface. But it apparently did not work as well as anticipated.

At least two of the stings were from the dangerous box jellyfish, which forced her to cut short her second of two attempts last year as toxins built up in her system.

At one point, with jellyfish particles everywhere in the water, Nyad changed strokes to keep her face out of harm’s way.

“There are so many jellyfish,” said another tweet. “Diana is swimming backstroke right now leading with the cap-covered part of her head to minimize contact.”

By day, the jellies receded, and she was able to resume freestyle swimming.

Nyad, who turns 63 Wednesday, is making her third attempt since last summer at a cage-less crossing of the straits.