Manly to Bundeena 36km

Swimming out through the mouth of the harbour, marathon swimmers face thirty-six kilometres of open Pacific coastline. The Manly to Bundeena 36km is an open water marathon swimming event staged in the coastal sea of Sydney, New South Wales, organized by Another Level Performance. It stands as an immense ocean journey tracing the city's entire eastern ocean threshold from harbour to secluded southern cove.

The 36km Marathon Course from Little Manly to Bundeena

Covering an uncompromising distance of 36,000 metres, this point-to-point crossing challenges either solo marathon swimmers or relay teams of two or four swimmers. Given the sheer length of the crossing and the demands of offshore navigation, every participant or team must be escorted by their own dedicated support boat throughout the voyage. Departing from Little Manly Beach, the route strikes out past the colossal sandstone gates of North Head before running south along the open Pacific coast. Swimmers chart a course across the mouths of three major harbours, traversing active commercial shipping channels while charting past world-renowned oceanfronts including Bondi and Cronulla, before angling towards the sand of Bundeena Beach.

Your support crew stays glued to your hip through these busy waterways, constantly steering lines and checking for marine traffic. Because the journey spans thirty-six kilometres, swimmers face an endurance test that frequently carries on well past sunset to finish in the dark under night skies. Maintaining mental focus through the rolling offshore blackness requires deep composure, but your accompanying boat's navigation lights shepherd you directly towards the shoreline. At the end of that nocturnal effort, you step onto the tranquil sands of Bundeena Beach, greeted by an intimate and relaxed gathering of local residents and supporters cheering your arrival.

Pacific Swells and Cliff Rebound along the Sydney Cliffs

Taking place in December during the southern hemisphere summer, the swim enjoys sea temperatures that hover comfortably between 20°C (68 °F) and 22°C (72 °F). Yet the offshore environment presents serious physical dynamics, greeting swimmers with rolling southerly swells and coastal winds that regularly shift as you pass open ocean bays. Powerful tidal flows race around the exposed headlands, demanding constant effort to maintain course. Along the precipitous cliff lines, open ocean waves slam against vertical sandstone walls and create strong backwash, resulting in disorienting rebound chop that churns the water into an unpredictable washing machine under your stroke.

Sydney Harbour Mouth: Defences, Boom Nets, and Sunken Submarines

Beneath the surface, between 1876 and 1922, active underwater minefields guarded the shipping channels of Port Jackson, controlled from an operational submarine mining station stationed at Chowder Bay. High stone fortifications crowned Georges Head, Fort Denison, and North and South Heads, where early colonial batteries watched over the channel. During the Second World War, a massive anti-submarine boom net was laid across the entire width of Sydney Harbour, stretching from Laing Point and Watsons Bay across to the artillery batteries at Georges Head. In the darkness of May 31, 1942, three Japanese midget submarines attempted a daring covert raid by penetrating gaps in that partially finished boom net. The submarine M-14 became hopelessly ensnared in the heavy mesh at the western end of the central barrier before being scuttled by its trapped crew. Decades later, in 2006, the forgotten ocean wreck of sister submarine M-24 was finally discovered resting peacefully on the seabed off Sydney's northern beaches.

Cabbage Tree Bay Aquatic Reserve: Tropical Corals and Kelp

Just one kilometre from the start, the waters on the outer side of North Head are safeguarded within Sydney Harbour National Park and the pristine expanse of the Cabbage Tree Bay Aquatic Reserve. Established across 17 hectares, the reserve is maintained as a strict no-take marine sanctuary where fishing, harvesting, or disturbing aquatic species is entirely forbidden. Below the surface lies an extraordinary mosaic of marine life, where sandy seabeds and rocky reefs meet dense kelp forests and vibrant seagrass meadows. Remarkably for these temperate coastal waters, the bay shelters a thriving colony of Pocillopora aliciae, a hard coral typically found in warm tropical seas. Tucked into this corner sits Shelly Beach, a sheltered, 100-metre west-facing cove naturally buffered from open ocean swells by an offshore reef on its eastern flank. Snorkelers and divers gliding through its clear, protected shallows often search out a submerged curio: an old motorbike resting eight metres deep on the sandy sea floor.

Little Manly Cove and the Oceanfront Life of the Corso

The shores around the staging grounds carry deep indigenous heritage. Ancient shell middens discovered beside Fairy Bower offer lasting archaeological evidence of Aboriginal coastal life, while preserved reburial sites are safeguarded within the national park grounds at nearby Reef Beach and the historic Quarantine Station. The swim's launch site at Little Manly Beach rests inside sheltered Little Manly Cove along the northern shore of Sydney Harbour. The cove has welcomed salt-water bathers since at least 1880, when early men's public baths were built along the western shallows, while its eastern end features a concrete boat ramp where support vessels slip into the harbour to rendezvous with their swimmers. Just a short stroll from the cove lies the energetic town centre of Manly, where the bustling pedestrian Corso connects the quiet harbour shoreline directly to the surf breaks of Queenscliff, North Steyne, and South Steyne. After preparing on the calm harbour side, swimmers step into the clear waters of Little Manly Cove to take their first strokes out into the ocean.