Check out the Prince's new naval uniform.
Prince William is getting ready for a life at sea with the Royal Navy in the latest stage of his military training.
From Monday, he'll be learning about sea safety, how to handle a boat and navigation, before spending five weeks at sea on board the HMS Iron Duke.
The Prince will be head of the armed forces when he's older, so he's trying to get experience with all three now.
He's already spent a year in the Army, and in April he qualified to fly military planes with the RAF.
A senior naval official said the Prince's attachment would be challenging, but he wouldn't be getting any special treatment.
Prince William has already qualified to fly planes like this Tucano T1
"If we treated him like some super VIP and tailored a programme for him and walked around on egg shells, then that would be difficult," he said.
"But he's not, he's going to come just like any other young officer and do all the things that young officers get involved in."
That will include sharing a four-bed cabin on the HMS Iron Duke and being woken at 6.30am every morning.
William isn't the first Royal to try a life on the ocean wave.
He's following in the footsteps of his father, the Prince of Wales, uncle the Duke of York, and grandfather the Duke of Edinburgh, who've all served in the Royal Navy.