Gary, I use a Minelab Excalibur 800, and I really like the way it works. Aside from being totally waterproof, it also has integrated headphones too. I have been using mine for over ten years. They have the Series 2 out now, but I am thinking you could get a used original series at a decent price. They come in a 10" and 8" coil. It has pretty good depth too, depending though on the size of the target, but I have dug coins at 12" easily.

Hello, I been using the GARRETT ATX with very good results both in and out of the water (fresh/salt) and it is waterproof up to 10', there is a video in YOUTUBE showing the ATX vs. the MINELAB SDC2300 in a salt water test and by far the ATX beats the SDC2300 here´s the link: https://www.youtube.com/watch?v=EVRUtDeWED8

One thing I like about the Excalibur is it is waterproof to about 200ft I believe. I forget actual spec. This makes it good also for shallow diving 10-20 feet of water.

i use a Tesoro Sand Shark.