When considering a snorkel to use while spearfishing, it is important to consider whether you will be freediving or scuba diving.
If scuba diving while spearfishing, you could consider one that makes it easy to breathe from and clear. Snorkels with a bottom purge valve make clearing easier. Other options for snorkels include splash guards on the top to keep water from entering the snorkel when you are on the surface looking for your prey.
A proper freediving snorkel should be used if hunting while diving a breath hold dive. These snorkels are simple tubes that can be moved aside and offer little resistance to the diver when freediving down to spearfish.