Snorkeling in May?

I am planning to visit family in Japan in May (after golden week) and wanted to take some time to visit Okinawa and perhaps go snorkeling. Do you have any suggestions for guides/tours? Is it too cold to even try, will I need a wetsuit? Do I need to purchase my own gear beforehand? I would prefer to avoid super popular spots even if it means fewer cool sights.

If there is a better place for me to ask let me know! I don't really know what I'm doing.

by SoftExam4229