Rapanui, better known as The Shag Rock or simply "Shag Rock" was a notable sea stack which stood at the entrance of the Avon Heathcote Estuary near Christchurch, New Zealand. The boating channel into the estuary lies on the northern side of the rock. Although not used as a shipping port, the estuary is accessible to large yachts despite the bar and difficult tidal conditions. The rock stood close to the southern shore just above the low tide level. It was a prominent landmark on the road to Sumner until it crumbled in the February 2011 Christchurch earthquake.