Trinchesia caerulea (Montagu, 1804)

15 September, 2006.
Lephinchapel Reef, Loch Fyne on the west coast. 
A 12 mm animal on the reef at 14 m. Water temperature 14°C.
Fuji E900 camera in Ikelite housing, 2 x Inon D-2000 flashes and Inon UCL-165AD CU lenses.

for more information about this species go to one of the links below
scottish nudibranchs

 nudibranchs of the british isles sea slug forum