An Iron Man suit, a speedboat and a ship, those are the three components necessary for a scene that looks like something out of a movie, but has been as real as life itself.
The Royal Marine Corps is a British military operations force, and they are testing a personal controlled flight device, as you can see in this video:
It is not just about technology, it is about skill, since the users of a suit of these characteristics need many hours of training to be able to maintain balance in the face of so much propellant.
Gravity Industries has shown three pilots in this way in a boarding operation of a ship. In the exercise, a jet-suit pilot launches from an inflatable in search of a medium-size boat, lands on the deck, and drops a ladder over the side for the rest of the team to climb. In a second, it demonstrates the ability to quickly go back and forth between the moving boat and the launch, landing in the small boat even in swell. In a third, three jet suit pilots land on the deck of this ship in quick succession.
They are not stealth operations, the suit makes a lot of noise, so the chances of landing undetected are zero. That means it’s not useful for landing on an enemy ship alone, but it can help with many salvage operations.
To function, the suit requires 5 to 10 kg of jet fuel, using jet gauntlets to perform the flight.