Spearfishing in Greece is really difficult. The quantities of marine species , are really running low year by year, and they get more syspicious (they disappear on site) every day. There are still some good places were you could make a decent catch, but sadly very few...Our main ``targets``are big black groupers, dentex (or bream ), snapers, sea bass (only in winter time), amberjacks and other Mediterranian species...Most decent greek spearo`s often dive bellow 25 meters (sometimes even bellow 35-40 meters), and their main techniques are aspetto,aguatto and rock to rock search...
As frogman said ,most islands in Cyclades are good for spearfishing (especially during summer time, for big pelagics, like amberjacks, yahoo and tunas),,,but a boat is essential in order to discover the ``good`` spots...And certainly the ability to dive DEEP...
Blueicarus...There are quite a few apnea schools here...Some are,,, HFL, AIDA, Apnea Academy...
You could also check the greekdivers community (
www.greekdivers.com), were there are quite a few people ,most willing to help you and answer any question ,you may have...
Take care, dive safely...