Until further notice, only SHA approved operators can take you out.
This is the guidance from the Thai authorities and, by the way, not limited to diving only but applicable to all tours.
Let me recommend a good operator that got the "badge":
Sea Fund Divers.
Reminder: The ‘SHA Plus’ Certificate means that at least 70% of staff at the venues and businesses have been fully vaccinated against COVID-19.
To be clear, I am not a staff nor a shareholder ot this shop. This is purely a friendly recommendation based on my experience with them as a customer.
The Diving bear.