I took this one while visiting the 2,322 sqm man-made Atoll Reef attraction at Ocean Park HongKong. Atoll Reef boasts possibly the largest collection of Napolean fish, to be found in any aquarium in the world.
It was a very rare sight to see a sea turtle in the midst of all the fish, and I was lucky to take the opportunity for this shot.
Of course observing and respecting the park's policies as well as trying not to harm the subjects, I needed to disable my flash and started experimenting on various settings.
It was most fortunate that the Sea Turtle was to swim to the exact window I was preparing my camera and settle down just along the side.
I had to swear at a few people who thought it would be funny tapping at the glass, but I eventually gained my composure and took the shot.
It's my first aquarium style shot, and I'm not going back there for another three years or so, so any helpful tips would be most appreciated.

EDIT: Recategorised