In the latter 1970s, I met a Dutch man named Jeroen Deknatel who was living in Phuket, Thailand. I had a lot of Dutch contacts after living for three years in the Dutch ABC islands in the Caribbean from 1969-72, and they led to me to some unknown but fabulous diving places..
I asked him if we could cross over the border into Burma and dive the Richelieu Rocks, but at that time the ruling junta had the border closed. He was hopeful that it would open while we were offering programs together, but it didn't happen until many years later.
As was my habit, I set up an exploratory so I would know what kind of program was possible.
I jumped on a plane and flew to Bangkok, a delightful city with two of the finest hotels in the world, fast boats surfing through the klongs, or interior canals and a spectacular Royal Palace. After a couple of dizzying days in Bangkok Then I flew down to Phuket and enjoyed the cornucopia of seafood and entertainment to be found there.
The diving was good and varied, but not really world class, and the boat was, um, primitive. Still, the overall adventure was wonderful, and we welcomed hundreds of our divers there over several years.
The Similan Islands have some current, which makes for colorful corals encrusting any free-standing rock. Most of the islands have barren, rocky terrain on one side of the island and a richly developed coral reef on the other side, with steep dropoffs into deeper water.
One spectacular resident on these reefs were brilliant purple Crown-of-Thorns Starfish.