There are several questions that you would need to ask yourself that will help you decide what type of underwater detector would be best for your hunting habit. They are:
- Where are you planning to use your metal detector?
- Will you be in salt or fresh water?
- What type is best for you?
- What accessories will be vital to carry along with you?
- How much will you need to spend?
For now, you may not be able to say where you will be using your underwater metal detector, you generally have an idea of how you plan on walking along a beach (either salt or fresh water), wading in water, or maybe you are planning on diving to check out ship wrecks. You, probably, are planning to use the detector on land and in water.
If you are going to use your metal detector near saltwater, for example, then you should plan to purchase a PI detector. You can also use a VLF, but you should make sure it has a saltwater mode. If you are going to be diving, then you should make sure that the depth rating (that is, how deep you can use it, and not how deep the ground it will search is) is deep enough for where you plan on using it.
As a diver, you might want to make sure that whatever model you choose has a short dive pole that would make your search a bit more comfortable. Other accessories you may want to consider are headphones so that you can easily hear the tones for objects that are deep and also help block out surrounding noises.
Most of the underwater detectors available on the market have a set of waterproof headphones with the metal detector. A bag to carry your metal detector in, sand scoops and a sifter will all make your treasure hunt easier and more fun.