A GUTSY grandma on a mission to save the Great Barrier Reef arrived in Mackay yesterday on a 1200km walk from Cairns to Gladstone.

June Norman, 72, said she was relieved to be on the "downward stretch" of her walk to raise awareness about the threats the reef faced from mega ports and industrialisation.

Ms Norman said she'd averaged 20km a day on her trek from Cairns.

"I'm a fairly fit person but I've had my health issues," she said.

She said while some family members labelled her campaign "a bit radical", she felt like walking was a great way to make a big impact.

"I've sent submissions and visited parliamentarians and chained myself to bulldozers but I feel like it's only when ordinary people step outside their comfort zones and stand up that we'll make positive steps to save the reef," she said.

Ms Norman said 30 people joined her on her walk into Mackay across the Forgan Bridge yesterday morning.

"Once you get over the initial aches and pains and blisters (walking) becomes quite meditative," she said.