Best mid-price water machine?

[beachboy]

What is the best Mid-price water machine? I would like to be able to take it under water.......3,4 houndred range.....

[Eu_citzen]

What kind of water? (i.e salt water, fresh water etc)

Where? (so we get an idea of mineralization)

What will you be hunting? (i.e coins, jewelry, relics etc)

Will it be used on dry sand/land as well? (used both in water and on land)

How deep under water?