A cool piece of technology

I recently received an awesome gift for x mas this past year. Its called a hummingbird portable fish finder. It is a green football shaped thing that you cast into the water. (e.g. a creek or stream) Then there is a watch that shows you what is in the water and how deep the water is. Traditional fish finders have to be wired to a battery on your boat and are expensive, but i can take this with me while trout fishing and see where the fish are on my watch. I will use this a lot this spring when trout starts. Sometimes while fishing I wonder if there are any trout left in the creek but now i will know for sure.