What lies beneath? The submerged secrets of the Hauraki Gulf – and why they need protecting

Ecologically rich, culturally vital and historically layered, the Hauraki Gulf is one of our most significant marine environments. Twenty times bigger than Lake Taupō, it stretches from metropolitan Auckland to the Mokohīnau islands and takes in Aotea Great Barrier and both sides of the Coromandel Peninsula.

After years of negotiation,
Parliament has passed legislation establishing 12 new high protection areas and five seafloor protection areas across the gulf with the Hauraki Gulf / Tīkapa Moana Marine Protection Act. High protection areas safeguard marine life, restricting fishing and allowing limited customary practices. Seafloor protection areas conserve the seabed, permitting low-impact activities such as line or spear fishing and diving but prohibiting trawling, dredging and Danish seining.

But although the new zones aim to restore ecosystems and biodiversity in the sadly diminished gulf, one dimension of the marine environment remains largely ignored: the cultural heritage that lies on and beneath the seafloor.

Within the gulf are remnants of centuries of human interaction, from ancestral waka routes and submerged Māori and European sites to wharf structures and wartime remnants. Each is a fragment of Aotearoa’s maritime story, offering evidence of navigation, trade, technology and cross-cultural encounters.

This underwater cultural heritage is fragile. Saltwater corrosion, biological decay, sediment movement, fossicking, anchor scouring, dredging, trawling and fishing gear can all cause rapid deterioration.

Once disturbed, context and meaning are easily lost. Unlike the biodiversity that these new protection zones aim to conserve, heritage sites cannot regenerate.

Despite this, heritage conservation rarely features in marine management discussions. The new legislation, for example, makes no direct reference to shipwrecks, archaeological sites, heritage or submerged cultural landscapes.

As with any zoning exercise, restrictions in one area inevitably shift use elsewhere and add to existing pressures. Boaties, fishers and divers will likely concentrate in the remaining “open” parts of the gulf – precisely where underwater heritage is most vulnerable. Anchors dropped on historic wrecks, fishing lines snagged on timbers, or trawl nets dragged across buried artefacts can inflict irreversible damage. So underwater cultural heritage may actually face greater risk through “displacement” of human activity in unprotected zones.

The Rewa, intentionally beached off Moturekareka Island in Kawau Bay in 1930, is a summer snorkelling mecca. Photos / Raewyn Peart

Legal protection for underwater cultural heritage is patchy. The Heritage New Zealand Pouhere Taonga Act regulates archaeological sites (including submerged ones) but relies on an authority (permit) process that typically responds to known or potential sites being affected by development. The Protected Objects Act governs recovered artefacts rather than those in situ, and laws covering maritime transport and marine reserves are not about cultural value.

The soon-to-be-replaced Resource Management Act provides for the sustainable management of natural and physical resources, including heritage, through regional coastal plans, but its application to underwater contexts is fragmented and often lacks enforcement.

The Hauraki Gulf Marine Park Act offers no specific processes or protections for underwater cultural heritage sites.

Crucially, New Zealand is not a signatory to the 2001 Unesco Convention on the Protection of Underwater Cultural Heritage, which sets standards for safeguarding historic shipwrecks and other heritage sites through in situ preservation and research.

Without a single, coherent legal framework, underwater heritage falls between the cracks of existing maritime protections.

Sunken heritage provides substrates for diverse marine ecosystems. Photo / Raewyn Peart

Missing knowledge

Because the seabed is largely invisible or inaccessible to most, underwater cultural heritage often goes unnoticed until it is damaged or lost. There is no comprehensive map of submerged heritage sites in the Hauraki Gulf. Rather, various databases and plans indicate a mixture of identified and possible locations. The few that are recorded, such as RMS Niagara off Whangārei Heads or SS Wairarapa on the northern end of Aotea Great Barrier Island, represent only a fraction of what exists. Other sites may just be points on a map with no official verification, leading to mismanagement and inaccurate guidance for customary, recreational or commercial activities.

This vagueness means that when marine protection areas are planned, heritage is rarely factored in or even appropriately considered. Environmental impact assessments tend to focus on biodiversity, water quality and fisheries, not archaeological or cultural heritage risk. The result is that management decisions are being made without knowing what lies beneath the surface.

Cultural heritage and environmental values are not opposites; they are intertwined. Many iwi and hapū see underwater taonga, such as waka, coastal pā remnants and ancestral seascapes as part of their living whakapapa and kaitiakitanga responsibilities.

Likewise, shipwrecks are often rich biological habitats. Iron hulls and wooden frames provide substrate for coral, sponges and kelp and support a whole wider ecosystem of species. In some cases, the ecological and cultural values overlap entirely. Managing one without considering the other is shortsighted.

Overseas, a more holistic approach is being adopted through marine spatial planning. In Australia, for example, the Underwater Cultural Heritage Act 2018, ensures cultural heritage is specifically considered in environmental management and marine conservation initiatives: ecological, historic, cultural and social values are managed collectively.

New Zealand needs stronger co-ordination between its legislative regimes. A more integrated approach would reduce fragmentation and support a cohesive, ecosystem- and cultural heritage-based framework for marine spatial planning.

Wreck Bay on Rangitoto Island is a graveyard for ships scuttled between 1887 and 1947. Photo / Raewyn Peart

Data trawl

The next phase following the passing of the Hauraki Gulf Marine Protection Act in October involves developing management plans and monitoring systems for the new protected areas. This is the moment to close the heritage gap with baseline surveys and mapping, involving iwi, councils, the Department of Conservation, Heritage New Zealand and the Ministry of Primary Industries. Ideally, these agencies could jointly develop protocols for identifying, reporting and protecting heritage during any marine management or development.

Once mapped – archives, geophysical scanning and diver investigations could all be used here – the data should inform zoning, the creation of buffer zones, permitted activities and ongoing management. For example, anchoring could be prohibited over identified wrecks or seabed structures; dive tourism could be encouraged in ways that support the monitoring of sites, education, conservation and citizen science.

Future management documents should explicitly recognise underwater cultural heritage as a value to be monitored and protected, and not as a byproduct of ecological conservation.

We also need communities to help. Kaitiakitanga principles and Māori traditional knowledge offer valuable frameworks for managing underwater taonga. Divers, fishers, tourist operators and maritime historians can also play an important role in reporting discoveries or damage. And, of course, there need to be clear rules and penalties for when damage occurs. Without meaningful consequences, heritage protection remains symbolic.

On land, we have learnt, often painfully, that heritage protection must be built-in from the start, not added later. Countless historic buildings, archaeological sites and cultural landscapes have been lost because planning systems failed to recognise their value until it was too late. We can’t let this happen with the taonga on our seafloor, whether in the Hauraki Gulf or other waters.

True guardianship should encompass both nature and culture – the living ecosystems and the deep histories intertwined within them. As we chart a path for ecological recovery, we must also ensure that the almost 1000-year-old physical and non-physical record of our maritime past is not lost beneath the waves.

Dr Kurt Bennett is a maritime archaeologist based in Auckland.

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