Forces TV's Rebecca Ricks has managed to stowaway aboard HMS Duncan as it became the first Type 45 destroyer to reach Greenwich.
Built by BAE Systems Maritime, Type 45 Daring-class destroyers are designed for anti-aircraft and missile engagements. 
Being some of the most sophisticated warships in the world, their decks and hulls are packed with some serious kit.
One example is the SAMPSON AESA radar beacons, which can track and defend against more than 2,000 aircraft and drones.
There's also the Seagnat anti-missile systems, designed to intercept and blow up incoming warheads.
The ships also tow SSTD (Surface Ship Torpedo Defence) equipment, while still leaving room below deck for 60 Royal Marines and their equipment.
The downside of all this gear, however, is the amount of room required to haul it.
There was concern that HMS Duncan might not have the leeway needed to navigate the narrow channels of the Thames on its way to port in the docklands.