As Nelson city grew, the suburbs spread onto the port hills and beyond. Tāhunanui also became a very popular beach resort from the 1920s, and access to the city along Rocks Road (built by prisoners between 1892 and 1896) was quick and easy. These houses on the hill facing Tasman Bay sit on the Tāhunanui Slump – a landslide that started moving a few thousand years ago. The landslide tends to move most during heavy rainfall, or ground shaking caused by earthquakes. Building restrictions mean that any further development on the active part of the slump is unlikely, as parts of it are still moving, albeit very slowly.