noun
diver certification card; C-card
Refers specifically to the certification card carried by scuba divers to prove their qualification level. The 'C' stands for 'certification'.
ダイビングショップでＣカードを見せてください。
Please show your C-card at the dive shop.
Ｃカードがないと、タンクを借りられない。
Without a C-card, you can't rent a tank.