Of course, if you know that you will be taking your underwater metal detector, well, underwater, then you definitely have to know just how far it will go until it stops working. The 2 most important factors to keep in mind when shopping are the depth and accuracy of the metal detector.
Depth
You do not want to just dive in, go farther than your detector would work and wonder what went wrong. Some of the products that you will find online as the best underwater metal detectors (we have an article on that on our website) are intended to be used for wading with just the coil will be below the surface, some have a small level of complete waterproofing while others can go great depths before they stop working.
When it comes to what depth is suitable for you, then this will depend on what activity you intend doing with your metal detector. If you never see yourself putting on a wetsuit and diving into the sea, then you obviously will not need a product that could go up to 250 feet below the surface.

If you are one that loves to scuba dive, then getting a metal detector can be a great accessory as you can go searching for gold while you look at the sights that are below the water. It is always best to err on the side of caution, though, and if you are caught between two options, then it might be best for your to go for the one that has greater depth since you never know when you will want to dive a bit deeper into the water.
Accuracy
Accuracy with metal detectors is one of the most important factors that you would need to consider when it comes to a detector and knowing how deep you are looking to go into the water is another important consideration. This can vary greatly from one model to another, so, it is vital that you check the product description as well as the user reviews before you settle on one product.