Cape Reinga is at the northwestern most part of New Zealand.
The road north to Cape Reinga is bordered on the west by 90 Mile Beach. The beach is not actually 90 miles but 90 kilometers. The popular explanation of this misnomer is from back when missionaries would travel by horseback to the northern cape. A general measurement was that horses could travel 30 miles (50 k) a day and this trip north took 3 days. The missionaries overestimated the distance due to the horses having a slower pace through the sand.
Near the end of 90 Mile Beach are great sand dunes. These dunes are hundreds of feet in the air and stretch on for miles. If one was dropped off here without any bearings they probably think they were in the middle of a vast desert.
Sand surfing is popular here which is using a small board to ride down the slopes of the dunes.