Prince William is expected to join Royal Navy patrols searching for drug runners in Caribbean waters during an attachment with the service.
The future King could also find himself helping to provide humanitarian relief if a hurricane strikes the region during his deployment on the frigate HMS Iron Duke.
William, 25, is said to be looking forward to the two-month secondment, which begins on Monday and aims to teach him about the Navy's ethos and capabilities as he prepares for his future role as head of the armed forces.
Rear Admiral Robert Cooling, Assistant Chief of Naval Staff, said the attachment would be rigorous and challenging but spoke with pride about Sub-Lieutenant Wales joining HMS Iron Duke.
The senior officer joked: "It will be a real thrill and privilege - not a pain in the ass - for the ship's company.
"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.
"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."
Pictures showing a smiling Sub-Lieutenant Wales in a dark double-breasted naval uniform with peaked cap have been released to mark the announcement.
He is following in the footsteps of his father, the Prince of Wales, uncle the Duke of York, and grandfather the Duke of Edinburgh, who all served in the Royal Navy.
The Prince - an officer in the Household Cavalry's Blues and Royals - will spend a number of weeks learning basic skills such as navigation, boat handling and sea safety. He will also briefly tour various units such as the Royal Marines and Air Fleet Arm, where he will have a chance to fly its helicopters.
