Te Whanganui-A-Hei Marine Reserve, at Hahei on the Coromandel Peninsula, was set up in 1992 and includes the Cathedral Cove arch. The DOC site says the reserve protects a wide range of habitats, from sandy flats to rocky reefs, and offers snorkelling and diving. Visitors can also swim, kayak and see the coastal geology. Kayaks can be hired at Hahei. The Cathedral Cove track leads to the rock archway, with views over the reserve's waters. A short walk from Hahei beach or the end of Pa Road leads to Hereheretaura Pā, with the remains of two pā sites in Te Pare Point Historic Reserve.
The reserve is about 1.5 hours' drive from Thames and about 2.5 hours from Auckland. Public boat ramps are at Hahei Beach, Whitianga and Cooks Beach. The rules are clear: no fishing, no taking marine life, and swim or dive in pairs. Snorkellers should wear a wetsuit and life jacket. Access to Poikeke and Motueka islands needs permission from Ngāti Hei. Our pick in Hahei for snorkelling near Cathedral Cove.