Rapid urban population growth and climate change are increasing the impact of coastal hazards and the demand on land space. Floating cities are one of the proposed solutions to alleviate the demand on land space and cope with rising sea-level. Floating cities and expanding coastal cities need protection barrier against violent sea-waves. Traditional bottom-connected breakwaters attenuate sea-waves, but they are uneconomical in deep water, and have adverse effects on the environment. floating breakwaters moored to the sea-bed are more efficient in wave attenuation compared to traditional ones. The goal of this project is to study the effect of different shapes of floating breakwaters on wave attenuation. Once large dataset is collected, machine learning will be used to generate predictive formulas for wave attenuation, which will help engineers optimize their designs. Finally, material reduction will be achieved by conducting topology optimization (TO) on selected shapes.