Where can I find free scuba diving photos without copyright, to use?

All images are copyright.

You can get royalty free images from stock photography sites such as istockphoto.com - but you need to pay for a licence to use them. Royalty free is not copyright free, nor are the images "free".

Another alternative is to seek free (as in $0) images licenced under Creative Commons. Use the creative commons search here: http://search.creativecommons.org/ - make sure you check the terms of the creative commons licence the image is issued under to stay legal.

MOST images are copyrighted, not all. You can source thing created by the US government, none of which are copyrighted. Many old photos from foreign countries have copyrights that expired 50 or 70 years after they were published or after the author died.

There are millions of non-copyrighted images; you just have to make sure you've actually found one, depending on how you plan to "use" them.

For instance, google images has stock that you can view for your own personal enjoyment, but you would need additional licenses (in most cases) to duplicate and distribute them anywhere else (i.e., to upload to any website anywhere).

Stock images but ull have to pay for them

Shutterstock.com