The Prince of Wales has visited the crew of Royal Navy survey ship HMS Enterprise in Japan.
Prince Charles also spoke to senior officials from the Japan Climate Leaders Partnership, and heard about efforts to combat plastics in the ocean and tackle climate change.
HMS Enterprise has been in the region to join a Japanese destroyer to test joint-capabilities east of Tokyo.
The British vessel met warship JS Teruzuki to perform combined maneouvres, sharing the lead role in several at-sea exercises.
She also launched her Seahawk helicopter.
The ship is taking part in exercises with Japan's navy, while also supporting the host nation during the enthronement of the new Emperor Naruhito.
Enterprise's constantly rotating crew is also rehearsing new supporting roles on board the vessel, which usually operates alone.
"It was a good experience for Enterprise’s sailors to sail so close to another ship as it is not something we do often," said Lieutenant Commander Jim Chapman.
In keeping with the cooperative spirit of events, man overboard exercises took place - where personnel responded to alarms on deck and deployed small rescue teams.
Able Seaman Jack Larkman jumped into the water from the smaller rescue boat and retrieved the dummy 'casualties'.
“As the swimmer, you have to be ready. Due to the boat being so close to the buoy, I was able to get into the water and be winched back out again in a couple of minutes."
Live firing exercises also saw the crew unload 200 rounds from HMS Enterprise's 20mm main gun - meeting contacts in the sea.
Japan has now stated that it will deploy vessels to the Middle East, though it does not plan to join a US-led maritime security coalition.
The UK is among the nations to join the mission, which is operating in the Gulf amid tensions between Iran and the West.