The ship that sinks "on purpose"

A heavy-lift ship is a vessel designed to move very large loads that cannot be handled by normal ships. Ships are supposed to float above the water. Right? Well not this one.
It spends all of its time just below the water on purpose.
Doing a job that we never expected. Because who knew you’d need something like this… until you do. Amazing. This is the Blue Marlin, a semi-submerging vessels capable of lifting another ship out of the water and transporting it.