Anzac voyage to bottom of sea
A Kiwi and an Australian have made history with an ‘‘Anzac Dive’’ to the bottom of the Mariana Trench and a celebratory a Vegemite sandwich.
Deep-sea explorers, New Zealand’s Rob McCallum and Australian Tim Macdonald, set the record for both of their home countries on April 8 when they ventured 10,925m to the bottom of Challenger Deep on the southern end of the Pacific Ocean’s Mariana Trench.
While down there they set another world record with a sandwich and a few Anzac biscuits.
‘‘It was a busy dive but we took the time to set a light-hearted world record; the world’s deepest ever Vegemite sandwich and Anzac biscuits, which is something only Australasians really understand,’’ said Macdonald, the pilot of the submersible.
The expedition aimed to test acoustic navigation equipment that will be used to aid deep ocean research.
The equipment will help researchers who rely on acoustic telemetry – using sound to relay information across open spaces – to know exactly where samples are collected. The divers also collected geological samples from the sea floor.
McCallum, an expert in deep water submersible operations who has been exploring oceans for two decades, said the pair had Kiwi mountaineer Sir Edmund Hillary in mind at a milestone during their descent. ‘‘We did spare a thought for Sir Ed as we descended through 8850m [the equivalent height of Everest] and still had another couple of kilometres to go,’’ he said.
‘‘It’s a very long way down and testament to the incredible engineering that has gone into this vehicle and to the team that support it.’’
The 12-hour expedition, labelled ‘‘the Anzac Dive’’, was completed in Caladan Oceanic’s two-seater submersible Limiting Factor, the only private full-ocean-depth vehicle in the world. It was used during the world record-breaking Five Deeps Expedition in 2019 that went to the deepest point in each of the world’s five oceans.
McCallum described it as a remarkable vehicle and a ‘‘true pathfinder to the last frontier of exploration on Earth – the deep ocean’’.
‘‘She will enable us to explore to any depth in any ocean and the discoveries she will make in the future are almost beyond comprehension.’’
The descent in the submersible, which can withstand pressures of up to 1400 bar (atmospheric pressure at sea level is approximately 1 bar), was a little creaky.
‘‘The sub does creak a little as it passes through 5000m . . . a result of the pressure being loaded on the hull at the rate of 400 tonnes per minute,’’ McCallum said.
Macdonald explained the pressure on the hatch alone is equivalent to 2200 tonnes, or five fully-laden 747 aircraft.
He said the vehicle ‘‘is poised to make some of the greatest gains in ocean science’’.
‘‘It both demonstrates our new ability to reach into the hadal zone [the deepest parts of the ocean],
but also of the importance that private funding will play in the future exploration of the deep ocean.’’
The wider expedition team – who work in areas including ocean mapping and science – consists of 34 people representing 14 nationalities. McCallum said the special bond between the Kiwis and the Aussies meant the name of the expedition ‘‘stuck’’ before they had permission to officially use it. ‘‘It was terrific to have an Aussie and a Kiwi work side by side. In that regard it was a very Anzac dive – two good mates from opposite sides of the Tasman working together under pressure’’ said Macdonald.