Depending on your experience level, you want to decide on the type of spear gun you buy. There are some more basic entry level guns for spearfishing beginners. They are great to learn and to try out the sport without going in over your head. You also need to consider your dive spot and the type of pray you are aiming for, when choosing a speargun.
Commonly, popular spearguns can be classified into two main categories: railguns and roller guns. Railguns have the advantage that they are easier to load and more accurate. A roller gun on the other hand gives you more power out of a shorter barrel.
Common materials include aluminium, stainless steel, carbon, and timber. The speargun is your most important tool, when hunting for fish. You want to make sure to get a high-quality piece from the beginning, which you can use for a long time.