This invention relates to a submersible vessel for dry docking a vessel. The submersible vessel comprises a floating unit, a deck above the floating unit and a number of stabilising towers arranged on the deck. The deck has a base, a sidewall along a perimeter of the base and a block provided within the sidewall and resting on the base, defining a cavity such that when the vessel is being docked onto the deck, a thruster of the vessel is above the cavity.