Sydney’s mystery beach at Mackenzies Bay

If you've heard whispers about a secret Sydney beach that appears out of nowhere and then vanishes again, you're thinking of Mackenzies Bay - the little cove tucked between the southern end of Bondi and Tamarama that only becomes a sandy beach when the ocean decides to deliver the sand. Most of the year it's a rocky inlet you'd walk straight past on the coastal path; then, roughly every few years, it fills almost overnight with a proper stretch of golden sand. Locals call it "Maccas", and catching it out is one of my favourite little thrills of living here.

Where

Between South Bondi and Tamarama, on the Bondi to Bronte coastal walk

What

A cove that periodically fills with sand to become a beach

When it appears

Unpredictable - sometimes for months, sometimes not for years

Nickname

"Maccas"

Cost

Free

Why the beach comes and goes

There's a persistent local legend that Mackenzies Bay shows up every seven years, but the truth is less tidy - and more interesting. The bay is a narrow east-facing pocket hemmed in by rocky headlands, which makes it unusually sensitive to what the ocean is doing. When low-pressure swells and offshore winds line up just right, they push sand into the cove fast, sometimes turning bare rock into a broad beach in days. When a big storm swell rolls in from the wrong direction, that same sand gets stripped straight back out to sea.

So there's no calendar for it. Some years the beach lingers for a few months; other times it stays hidden for years on end. That unpredictability is exactly why it's earned its "mystery beach" reputation.

The legendary years

Old-timers still talk about 1997, when there was reportedly so much sand that at low tide you could almost walk from South Bondi around to Tamarama. That golden run ended when a major east-coast storm battered the coastline and the sand vanished - and it didn't return in any real way until 2007. It's this boom-and-bust rhythm, rather than any neat seven-year cycle, that defines the place.

How to find it and what to expect

Mackenzies Bay sits on the Bondi to Bronte section of the famous Bondi to Coogee coastal walk. Start at Bondi's south end near the Icebergs, follow the clifftop path towards Tamarama, and the bay opens up below you - you'll pass Mackenzies Point, a rocky lookout with some of the best whale-watching views on this stretch of coast.

• There are no lifeguards, no flags and no patrol at Mackenzies - it is not a patrolled beach, so treat the water with real respect.
• The cove is ringed by rocks and can have strong currents and sudden shore-break; if you want a safe swim, the flagged beaches at Bondi and Bronte are close by.
• When the sand is in, it's a favourite with surfers, sunbathers and dog walkers - but conditions change fast.
• The clifftop path above the bay is one of the best free vantage points on the eastern beaches, sand or no sand.

For me, that's the real charm of Mackenzies. In a city where almost everything is mapped and booked to death, here's a beach that still does exactly what it wants. The walk is worth it either way - and if you catch the mystery beach in full glory, you'll have seen something plenty of lifelong Sydneysiders never have.