It's interesting to see which cultures around the world hold spearfishing important enough to put on a stamp. More commonly it's traditional spearfishing rather than underwater hunting. French Polynesia leads by far with 5 entries.
Anguilla
Barbuda
Canada. You wouldn't have thought it eh
Chile
Comoros Islands
Cuba
Djibouti
Fiji
Finland
French Polynesia
Grenada
New Zealand
Palau
Panama