This was taken in a vertical cave known as "the Chimney" at Sail rock in the Gulf of Thailand.
I missed the Cave competition but really wanted to share this picture which is one of my favourites.

It was taken on a Canon Ixus 800 with an Inon fisheye lens.
Edit: here is the link incase the image isn't loading (strange because it is working for me).
http://www.pbase.com/image/83991135.jpg
I don´t see the attachment...
I don´t see the attachment...
Thanks for the heads up, it seems to be working ok as far as I can see but I've added a link anyway.