A heavy-lift ship is a ship designed to move extremely heavy loads that cannot be handled by normal vessels.
Ships like the Blue Martin, a semi-submerging vessel capable of lifting another ship completely out of the water, travel the seas lifting heavy loads every day.
The Blue Martin can lift large ships like the USS Cole.
Or even this oil rig.
The Sea-Based X-Band Radar (SBX-1) is a floating, self-propelled mobile active electronically scanned array radar station that is designed to perform in high winds and heavy seas.
These drilling rigs have a grid work of iron beneath them which creates a giant footprint allowing them to stabilize the weight.