KOH SAMET HOTEL GUIDE BOOK Scuba Diving
While Koh Samet is not as famous at other islands in The Gulf of Thailand for Scuba Diving, it does offer excellent dive sites for beginners and lovers of the sport.

There are several PADI accredited dive centers on the island and all offer exciting dive trips, certification courses and even professional level courses - and much cheaper than if you were to take said courses in your home country. Needless to say, taking part in a PADI sanctioned course will ensure that the quality is high and safety guaranteed.

Recommendations from fellow travelers
You can contact a local tour operator in the island that caters Scuba diving and etc. There's the nearest small island off in Samet. Like Ko Khudee, Ko Talu that has pretty marine life. Though, I'm not allowed to dive after my Baby A. The operator told us that those islands has something to offer to.

I've seen an operator that offers for rent equipments for scuba diving.