Global climate change is expected to cause sea level rise, which will have major effects on Singapore because it is a small, low-lying island state. With the high degree of urbanization and industrialization on the island, land is scarce and very valuable. Examining three sea level rise scenarios for the next century, we explore whether Singapore should defend their coast or allow it to be inundated. Across ten coastal sites representing all market land in Singapore, we found that protection was the lowest cost strategy. The annual cost of protecting the coasts of Singapore will rise over time as the sea level rises and will range from 0.3 to 5.7 million US$ by 2050 to 0.9 to 16.8 million US$ by 2100. The present value of these costs ranges from 0.17 to 3.08 million US$ depending on the sea level rise scenario.