The Royal Navy has unveiled its first uniform overhaul in 20 years.
The crew of the HMS Daring are using the new kit on counter-piracy operations in the Arabian Gulf.
Known as the Number 4 dress, the dark blue uniform replaces the familiar light blue outfits.
The Ministry of Defence said the uniforms are designed to adapt to the different conditions faced by the Navy at sea around the globe.
Among the upgrades are the addition of slanted pockets on the legs to make them easier to open while sitting down, and new baseball caps as well as more traditional hats.
Boots have zips and not laces, to make them easier to put on quickly, and collars are made with Velcro.
Rank badges will be form on the front of the uniform and not on the shoulders, as is more traditional.
Lieutenant Commander Ben Hughes, HMS Daring's Logistics Officer, said:
"So far the reaction on board the ship has been very positive. It is a comfortable, practical uniform that looks much more modern than the old style.
"The boots are very comfortable as well, especially for people who are stood on their feet all day and with the zip it makes it easier to just pull them on and off."
The uniforms will be made by a British company, and other trials on Type 23 Frigate HMS Windsor and Trafalgar-class submarine HMS Talent will follow.
The new uniform is being manufactured by a British company as part of a £250,000 contract. Similar trials of the new uniform are due to take place on the Type 23 Frigate HMS Westminster and the Trafalgar class submarine HMS Talent.