Just went to Ao Phang Nga National Park (James Bond Island), and upon arriving was asked to see proof of vaccination (they were fine with a picture off my phone) and also asked if I had my third shot, which I said I had just got my vaccine in September and I was free to go.
Not sure if it’s just here or other National Parks as well
TLDR : Answer Summary
Upon visiting Ao Phang Nga National Park, proof of vaccination is required for entry, and a photo of the vaccination card is acceptable. Visitors may also be asked if they have received their third vaccine dose. This policy aligns with national guidelines for parks and may be consistent across other national parks in Thailand.