To a seasoned runner, a 420-metre dash might seem like a walk in the park.

But try it up one of Sydney's steepest streets and you've got yourself a challenge, and personnel from HMAS Penguin took up that challenge on May 29.

The Balmoral Burn, which is in its 20th year, is an annual community fun run - or walk - up Awaba Street near Balmoral Beach in the suburb of Mosman in support of the Humpty Dumpty Foundation.

Commanding Officer of HMAS Penguin Commander Michael Nipperess received an invitation for Penguin crew members to participate in this year's event.

Without hesitation personnel, their family and friends signed up for the challenge.

"HMAS Penguin later this year celebrates 80 years as an establishment, with a proud history of supporting the local community, and it was a pleasure to be able to do that again," Commander Nipperess said.

At its steepest, the gradient of the route is nearly 30 percent, rising about 70 metres over the entire length.

Warrant Officer Chris Wright, from the ADF Diving School, was keen to take on the steep climb.

"I remember having to run up there every week when I was doing my basic training, but we did it carrying a berthing hawser." Warrant Officer Wright said.

"Today, my two young boys ran up the hill as well and it was great to see them cross the finish line with such big smiles."

Former Wallaby Phil Kearns founded the event as a thank-you to the staff of the Royal North Shore Hospital after his son Finn received emergency care for suspected meningococcal.

What started off as a few people getting together to run now has a cult following, and is growing every year, with a run/walk category to suit all ages - and even one for pets.

The Humpty Dumpty Foundation is a children's charity that, for more than 30 years, has been purchasing lifesaving medical equipment used to treat sick and injured children in paediatric wards, neonatal units, maternity and emergency departments in hospitals around Australia.

The HMAS Penguin crew after competing the Balmoral Burn. Photo: Leading Seaman David Cox