Build your own Hydrophone is a great website for do it yourself ideas.

see examples below.

Here is a great design for an underwater Hydrophone

Also here is one for an underwater housing – however it would be best to bolt and glue the window into the box. An ammo case is a steel box that can be bought in disposal stores ie Army Surplus.

Underwater Camera link is here

And here is how to photograph in the ultraviolet spectrum