There are more advantages to these miniature underwater data centers. Seafloor-based pods don’t require expensive commercial real estate, and they get nearly free cooling from the surrounding tons of seawater.

The logistic advantage may be even more important than the cooling or immediate financial one. It takes significant time and specialized effort to acquire and develop commercial real estate for a traditional data center in a major citybuilding a sealed pod and deploying it on the seafloor nearby should be considerably simpler and faster.

Source: Microsoft declares its underwater data center test was a success - Ars Technica

This is really cool.