The most complicated part of a speargun is the speargun trigger. In saying that however, the trigger by itself is just a piece of metal. The trigger connects to a series of parts that make up the trigger mechanism. The speargun trigger joins to, and engages the trigger mechanism to perform the firing action of the speargun.
The trigger mechanism is housed by the handle and handle frame. The speargun trigger mechanism is made to high standards and can withstand over 500Kg (1200 pounds) of loading strain, that's a lot considering that even high powered spearguns will never come close to using that amount of strain. It is for smoothness of firing and safety reasons that speargun trigger manufacturers choose to make such strong trigger mechanisms.
The average spearfisherman would not worry about the type of speargun trigger or trigger mechanism they are using. Most spearfisherman buy a pre-assembled speargun, replacing the speargun or getting it repaired if something breaks. Some spearfisherman however prefer to build and repair their own spearguns. This gives them a choice of which speargun trigger and mechanism to use. There are a few different types of speargun trigger mechanisms available, all are of high quality and strength. Where these trigger mechanisms differ is the design, the inner workings and the way they operate.