two large cruise ships - anthem of the seas and explorer of the seas - both sailing out of southampton this summer .
the liners , both owned by royal caribbean , were spotted passing each other in southampton docks earlier today .
the anthem of the seas is now the world 's largest cruise ship with room for nearly 5,000 passengers and 16 decks .
sister ship , the explorer of the seas , has recently undergone refurbishment and will sail around the mediterranean .