A MONSTER 6.4-metre king tide couldn't stop Emma Johnson and Grace Schembri hitting the surf.
The cousins were at Harbour Beach on Saturday to watch the waves roll in.
Emma's mother Therese Johnson said the visit to the beach was an opportunity for the girls to learn how the pull of the moon affected the ocean's tides and currents.
"They probably notice it more when we go over bridges," Ms Johnson said.
"They were talking to their uncle about... how it's hard to fish in a big tide," she said.
Emma said the best part of the king tide were the waves.
"It was pretty cool," she said.
The tide hit its maximum at Mackay Harbour at 11.10am on Saturday.
King tide is not a scientific term, rather a phrase with Australian and New Zealand origins which describes the very highest of tides in a season. Coastal communities around Queensland were encouraged to take photos of the ocean as part of the Green Cross King Tides' project.
The project aimed to create a comprehensive collection of photographs to help understand what changes could occur on the coast as a result of climate change.