Kaikoura Peninsula is made of limestone and siltstone laid down beneath the sea about 60 million years ago – but it has been exposed to the elements for a mere 180,000 years. Once an island, it is now linked to the mainland by debris eroded from the Kaikoura mountains, These mountains are rising faster than any other mountains in New Zealand (10 mm per year) but erosion keeps their height fairly constant.
Periods of rapid uplift have formed the steep-sided promontories, ideal for pā sites, and have twisted the neatly layered limestone into unusual shapes. The relatively young rocks have been worn into many interesting forms by the pounding sea. In less active periods, the sea has cut large tidal platforms in the softer sandstone.
Offshore is a very deep underwater canyon system called the Hikurangi Trench. It comes unusually close to shore at Kaikoura, where it is known as the Kaikoura Canyon. The canyon floor collects sediments that will form tomorrow’s rocks and may appear in millions of years’ time as new mountains.
Jutting out around 4 km from the shore and sculpted by numerous rocky headlands and small, semi-sheltered embayments, the peninsula presents a wide variety of aspects depending on the weather.
Rocky outcrops, wavecut mudstone platforms incised with guts and channels and tortured-looking limestone reefs are interspersed with boulder reefs and small, crescent-shaped, stony beaches. The reefs, so prominent at low tide, continue for hundreds of metres offshore, eventually breaking up into flat expanses of pebbles, which eventually terminate in sand and mud further offshore
The peninsula is a biological nodal point, a place where 'north meets south' or, more accurately, where 'warm meets cold'. Here, the distributions of typically northern and southern species overlap – the seaweeds show a strong southern affinity, while the animals show a warmer, more northern influence. Add to this the rich variety of intertidal and sub-tidal habitats, and you have one of the most biologically diverse locations of the entire east coast of the South Island.
Firmly anchored to the rocks, bull kelp forms a distinctive fringe along the low-tide mark, its dense mass of leathery fronds swirling snake-like in the waves. Kelp and numerous other seaweeds thrive in the pulsating light zone of Kaikoura’s nutrient-rich coastal waters and, along with phytoplankton (microscopic plants), form the beginning of the marine food chain.
Koura (crayfish) shelter in rocky crevices and under boulders around much of the peninsula; these are some of Kaikoura’s best known marine creatures and lend their name to the town. Ranging from barnacles, limpets and crabs to paua, sponges and fish, the multitude of marine animals found at Kaikoura Peninsula is simply remarkable.
Hutton's shearwater colony
This colony, adjacent to the walkway, provides a sanctuary for these unique birds and a special opportunity for visitors to experience the delight of an active sea bird colony, especially at night when the birds return from feeding at sea.
Thee 500 m long, state-of-the-art predator-proof fence keeps out introduced mammals such as rats, cats, possums and stoats as these burrow-nesting birds are particularly vulnerable to predators.