The Nelson Boulder Bank, visible off the Nelson coast in this south-facing view, stretches 13 kilometres into Tasman Bay in the northern South Island. It is composed of pebbles and boulders up to 1.2 metres in diameter that have originated from Mackay Bluff at the northern end. During northerly storms the boulders are moved south-west along the bank. Radiocarbon dating shows that the bank has developed in the 6,000 years since the sea rose to its present level.