Safe carbon dioxide (CO₂) storage is likely to be critical for mitigating some of the most severe effects of climate change. We present a simulation framework for modeling CO₂ storage beneath the seafloor, where CO₂ can form a solid. This can aid in permanent CO₂ storage for long periods of time. Our models show what a commercial-scale CO₂ injection would look like in a marine environment. We discuss what would need to be considered when designing a subsea CO₂ injection.