The final swimmers powered on, one with a yellow rubber duck attached to her cap so it seemed to bob along the water at unnatural speed.

There was a horse involved in the event somewhere, swimmers in shower caps and a woman dressed as a cow.

The annual event, where teams swim relay-style for a full day, raises money for scholarships for people with multiple sclerosis.

Anita Graham, an organiser and participant, swam for her team for about an hour and a half, starting at 2am.

"I had the graveyard shift," she said, her voice hoarse.

"It hurt but it was actually quite peaceful and quite relaxing at that hour."

Donations resulting from this year's swim passed $39,000 yesterday, bringing the Wollongong fund-raising total to more than $120,000 after three years.

Peter Brown, chairperson of the Figtree Lions MS committee, which organises the event, said recipients used scholarship money to fulfil goals relating to employment, education, travel, the arts, sport, music and maximising their strength.

"When we see the scholarships given out, the hard work is worth it," he said.