That was my thought:
1. ALWAYS keep the speargun pointed in a safe direction (Note: your own face is not a safe direction! Neither is your wife, even when you are “cleaning” the speargun and “didn’t know it was loaded”).
2. ALWAYS keep your finger off the trigger until ready to shoot.
3. ALWAYS keep the speargun unloaded until ready to use.
A fairly basic question that I have is - How could he NOT have known the spear gun was loaded?