Tunnel Beach

BY KYLE BLAND (GNS)
Accessibility: MODERATE
View of the coastal cliffs and sea arch from the Tunnel Beach track (Photo: Kyle Bland)
A wild and spectacular location with an interesting geological and human history
Looking down the tunnel of Tunnel Beach (Photo: Kyle Bland)
The 30 m-high cliffs at Tunnel Beach are formed from early- to middle-Miocene Caversham Sandstone, part of the Otakou Group. Caversham Sandstone is a 'clean', well-sorted marine sandstone that was probably deposited in a marine environment similar to that of the present day Otago Shelf. The coastline at that time would have been well inland of where it presently lies. The retreat of the coastline to its present location during the last 20 million years is due to the combined effects of tectonic uplift, and possibly to subsurface doming by intrusions under the Dunedin Volcano.

The tunnel was excavated in the 1870s by John Cargill (a son of Captain William Cargill) so that the family could bathe at a secluded location away from the prying eyes of St Clair residents. Sadly, Cargill's youngest daughter drowned at the beach, after being caught in a powerful rip current.

The prominent sea arch and sea stacks have been formed by the powerful forces of waves and erosion.
Near horizontally bedded Caversham Sandstone (Photo: Kyle Bland)
Within the sandstone layers you may see shell fragments, brachiopods (lamp shells), sea urchin fossils, and possibly even whale vertebrae. The sandstone also contains trace fossils, which are evidence of marine animals that once lived within and on top of the sediment as it was being deposited. Try to imagine what type of marine life swam above this site all those many millions of years ago!
Directions/Advisory

Tunnel Beach is located just south of Dunedin city centre. It is accessed from the car park on Tunnel Beach Road, signposted off Blackhead Road. From the car park, follow the fenced track downhill to the spectacular, rocky coastline. At the end of the track a short tunnel with steps leads down to a secluded beach.

The car park is reasonably small. If you have a large vehicle (e.g. a camper van), it can be difficult turning around, especially if the car park is full.

Don't leave valuables in your car – there have been break-ins!

Note that the path down is steep and can be very slippery following wet weather.

Keep well clear of the cliff edges. The beach itself is unsafe for swimming due to strong currents.

Google Directions

Click here for Google driving directions

Accessibility: MODERATE

Access to the beach is via a formed track across private farmland. Please respect the landowner's property, and remain on the track at all times. The track descends from an elevation of 150 metres above sea level, winding downhill for about 1.2 km to the top of the tunnel near a natural sea arch. The tunnel descends 72 steps to the beach; it is dimly lit, so a torch may be helpful.

Allow 10–15 minutes to walk down hill, and 20+ minutes back up hill!

Features
Sedimentary Fossils Landform Active Erosion
Geological Age
Miocene
Zealandia Evolution Sequence
Māui Supergroup (Emergence): 25 – 5 million years ago
Links