Spearboard
Heres a list of things other than a speargun&stringer.
1.Comfortable gear and adequate enviromental protection,spearfishermen tend to spend a lot of time in the water and around a lot of sharp stuff.Wrecks ,coral,concrete,rocks and fish can cut,sting or puncture your skin.Chafing and binding caused by poor fit makes a good day into a PITA.
2.Good buddies...a very under-rated commodity.Like minded hunters looking for similar game under similar conditions.Most freedivers or beginners will not be too at home in 130'+ looking for typical SE US game on the bottom.Just as many hard-core guys rarely dive in 30'
3.A good sense of ethics.You will be representing other spearfisherman to those around you.Do us all a favor and hunt responsibly.It means a better rep for us and abetter fishery for everyone.
4.Money.Setting aside enough cash to buy gear is only the beggining.There's air fills,gas for the boat or money for charter trips,ice for the catch,a freezer on the porch or in the garage is nice to keep spouses happy.I figure it costs about $20 per person on an inshore easy day to over $100 on long trips.Charters run $60 to several hundred for multi-day trips in distant waters.
5.Most inportant is a relaxed attitude and sense of humor.This after all still supposed to be fun.