The potential impacts of rising sea levels on the harbour town of Walvis Bay on the Namibian coast are considered. Walvis Bay is an arid, semi-desert environment with most of the town lying 2 m above mean sea level. The town is sheltered by a large sandy spit from the prevailing wave climate, which, on the open coast, can be quite severe. The area has an exceedingly dynamic sediment budget and is completely reliant on a small coastal aquifer for freshwater. This paper demonstrates the vulnerability of semisheltered environments to sea level rise and the need for accurate sediment budgeting in any Potential Impact Assessment.