It was right at the high tide mark, and the tide was "dead low" while they were rescuing it.
The whale, believed to be a female pygmy sperm whale, was "badly sunburnt" and bleeding. The first people there had wrapped it in sweatshirts and were pouring water on it.
A member of DOC arrived just before Mr Williamson.
The group rolled the whale on to a tarpaulin and carried it to the water.
"The girls struggled a fair bit, it was bloody heavy," he said.
Mr Williamson and the DOC employee walked the whale out to waist depth and held it for about 40 minutes to an hour, but as Mr Williamson was swapping with another man so he could go back to the shore, the whale swam away.
"It was pretty cool."