Two of them confessed to their crime after turning themselves in to the police while another suspect remains at large, The Phuket News reported.
They were part of a 30-member diving tour group to the island of Koh Racha in south Phuket late last week.
Photos of them picking up starfish and stepping on the coral reef were posted on Tuesday on a Facebook page called "Monsoon Garbage Thailand" that tracks environmental transgressions.
The photos quickly went viral on social media, with many people calling on Thai authorities to investigate.
The Facebook page said it received photos and video clips from a "Samaritan."
According to Thai law, anyone who harms or disturbs coral reefs or marine animals can be fined up to 100,000 baht and jailed for up to two years.