I’m in no way suggesting anything, nor encouraging or endorsing any particular course of action, but I do note that when things are securely tied to or wrapped in a heavy object with negative buoyancy, they do sink rather fast to the bottom of the sea and stay there. Examples of such things include battleship chains and concrete boots.
There is quite a bit more than just the cooling system in the picture. Coax cables take control signals from room temperature to the quantum processor and readout signals back. The signal paths include attenuation, filtering and amplification in various stages. The processor itself is in a magnetic shield, which is the grey cylinder at the bottom.