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A close-up image of a squat lobster under UV light. Every hair and ridge and groove on this fantastic little crustacean jumps off the screen when lit with UV light in the night
 

Most of my diving is done around the coasts of Scotland, and this is mainly in the sea lochs of the west coast. The variety of underwater habitats and life to be found here is just incredible. There are always surprises, even at the most frequently dived sites. I am particularly interested in biofluorescence in marine life and have been capturing images and video of underwater fluorescence in Scottish seas since 2014. I am constantly amazed by the variety of species that fluoresce—sharks, skates, crustaceans, anemones, tunicates, fish, to name a few—and the wonderful colors they can produce.

My winning image was taken in early December 2024 during an evening dive at one of my favorite sites: Inveraray, Loch Fyne. With the sun setting at about 3:30pm, the short days of the Scottish winter are perfect for fluorescent night dives. The site is known for being home to many beautiful fireworks anemones at relatively shallow depths, which makes it popular with underwater photographers from all over the UK. It’s not just the anemones that make this a fantastic site though; there is also an old pipe covered in concrete blocks that is home to lots of life, including spiny squat lobsters.
 

Prepped and ready to go! The author’s underwater fluorescence rig, equipped with specialized fluoro filters and UV lights
 

I did two dives on the evening in question. The first I had gone in with my wide-angle fluoro setup with the aim of mainly photographing the fluorescent fireworks anemones, which was a success. So, for the second dive, I decided to change over to my macro setup, an Olympus OM-D E-M1 Mark III with the Olympus M.Zuiko 14–42mm f/3.5–5.6 EZ pancake lens. For lighting I used two Sea&Sea YS-01 Solis strobes with Nightsea excitation filters. I also used a pair of Light & Motion Sola Nightsea lights mainly as focus lights. The barrier filter I used was a Lee 101 gel filter. I also brought my Nauticam CMC-1 for some extra close-up shots.
 

A squat lobster perched at an opening in a concrete reef ball
 

Under UV light, these squat lobsters glow brightly—stunning against their dark surroundings
 

The main focus of the second dive was the spiny squat lobsters that live in the concrete blocks of the old pipe covering. These squat lobsters are usually found clinging upside down on boulders/overhangs and are normally very skittish, disappearing the instant you get close enough to compose a shot or just before the shutter is pressed. However, on these night dives, they were wandering about in the open and didn’t seem to mind having a few pictures taken.

Most of the squat lobsters were on the concrete blocks but the individual in my winning image was wandering out in the open sand/mud substrate. These squat lobsters show the brightest fluorescence I have seen in any crustaceans so far. While the concrete with encrusting pink algae can provide a colorful background, I liked how this one really stood out against the plain background.
 

The author’s award-winning image. This picture was the runner-up in the British Waters Macro category of the Underwater Photographer of the Year 2025 compeition and James won “Most Promising Up-and-Coming British Photographer” with this image in the same competition
 

To see more of James’ images of fluorescing critters from Scotland and beyond, check out the fluorescence section of his website. Please also give him a follow on Instagram.