>>40760788
My tought is they are assembling an underwater base with multiple modules. Remember the Nimitz incident :

>Fravor and Slaight both looked down and noticed a disturbance in the water, like what you’d sea for waves breaking over an underwater seamount. It was an otherwise clear day, with calm water, so this whitewater patch was readily observable.

>Fravor described the disturbance as a large cross shaped patch of whitewater, like a 737 plane submerged slightly underneath the water, with waves breaking over it