The Barmah wetlands may not be quite as dramatic as the Amazon or Antarctica - her previous run routes - but for Guli it's a welcome trip home.

Raised in Melbourne, Guli now runs extraordinary distances in stunning, arid landscapes and rainforests to highlight the scarcity of water worldwide. Her early path from Monash University to stints as a lawyer took a sharp deviation when she set up the Thirst organisation in 2012.

Her energetic campaigning has brought her several global accolades including Fortune's 50 World Greatest leaders of 2016. (Guli's at 45, three spots ahead of Justine Trudeau. Rosie Batty comes in at 33.)

This week the lawyer turned activist drove straight to Echuca after disembarking from a series of plane trips from remote parts of Brazil. "I've run down the Colorado and the Amazon so I've literally arrived in Australia from the depths of the Amazon rainforest where I was criss-crossing the river," she says sounding not the least bit weary, despite a nagging toe injury.

She just had time to give her mother and sister a hug at the airport before heading off with her support team, including a blogger, a videographer and an all-important podiatrist.

The Murray River run is the third of six river marathons in six continents Guli's undertaking in just 40 days. Next up are the Yangtze, Nile and Thames. Echuca marks day 14 of the project. With 651 kilometres behind her, she has 1037 to go.

In her week in Australia she was due to run around the old port of Echuca, traverse the Barmah National park and finish at Yarrawonga on Saturday.

With about a week in each location, there's barely any time at all for her body to recover. The 40 marathons in 40 days figure ties into her core campaign statistic. "Experts predict that by 2030 there will be a 40 per cent difference between demand and supply for water. Last year I did 40 marathons in 49 days, but this time because the water issue has become even more urgent I want to represent that by doing it in a shorter time."

Guli's previous project, completed last year, took her through seven deserts, including Australia's Simpson, the Atacama in Chile, Jordan's Arabian Desert - and the polar "desert" of Antarctica.

This year it's river runs that propel her activism. "In Brazil we met people who live in floating houses on the river banks, kids who go to school by boats, my support vehicle was a boat. In a place like the Colorado it's far less remote. We met people in the tourism industry and a lot of farmers. Here in Australia it's a mix of farmers and tourism people and paddle boaters and people who have seen changes in the Murray from the air."

In Antarctica she spent time with Australian meteorologists and researchers at Casey Station and ran "carefully and slowly" in the snow. "Most people don't understand why I'm doing this and look at me with great incredulity," she says.

Disbelief is the first reaction that springs to mind. At a rate of a marathon a day, the wear and tear on her body at 46 is hard to imagine. Yet she's chipper to the last. "If I think that tomorrow I have to go and run another 52 kilometres it all becomes overwhelming, but if I just do it, and put one foot in front of another, it all just happens."

It's all to raise the profile of Thirst.org staff, interns and almost 900 volunteers, who present programs in schools to educate thousands of children in China about saving water.

Now based in Hong Kong, Guli speaks of an "invisible water footprint"; the amount of water embedded in everything we consume. "The water that goes into what we're wearing right now, and in your mobile phone, all of that took more water to make than all the water we've drunk in our lifetime."

It's for this she left behind the boardroom to meeting farmers, children, parents and experts. Guli arrived in China via law, banking and an investment fund, Peony Capital. Nominated for her climate change work by the Davos-based World Economic Forum, she joined its Young Global Leaders community.

"I realised that while climate change was urgent, water was extraordinarily urgent???I started Thirst.org in China because it's the fastest growing consumer community in the world, yet China has 300 million people who don't have enough water to drink. At the same time almost all of us owned products made in China so we're all connected to China's water problems."

Perhaps it's inevitable that given social media's short attention span, online the Thirst message arrives as a glossy product, event banners and children draped in the logo. Meanwhile all Guli's mini-epics are slickly documented - photographs and well-directed footage of Guli dwarfed by majestic landscapes. The Murray it seems is in good global company.