That must have been a very very big dive boat to carry 30 divers, divemasters/marshals, boat crew and all diving gear. The logistics of that would be more than a challenge. Sure they weren't Burmese passengers hope to get to India?

Some troll posts and replies have been removed. 

The Indians dont mess about and have an efficient, well bloodied military unlike Thailand whose military only fight Thai citizens except last century when they declared war on the British.

Time for Thailand to get the submarines out

Ah, a cunning Thai plan to declare war on India ? Well, now we know why Thais are buying armaments for the apocalypse 

It must have been a dive charter boat without permission. In Indian (Andaman) and Burmese waters (I have been to both) the military patrol vessels contact every vessel they see and make radio contact prior to onboarding for checking of permissions. 

 

I assume the Thais either ignored the radio or did not turn it on.

 

On "Leo" island, my guess would be a mis-understanding on the Thai media or dive boat part in terms of language. I would guess they were near the Cinque islands in the south. Cinque - Singh (Thai for lion).

Aren’t there Thai submarines patrolling this area to prevent this?...

Im afraid the Indian navy is far better equipped than the Thais they would just blow them out of the water my guess the dive boat ignored any warnings they got