Ranong and the Thai - Myanmar visa run. most travelers know the biggest harbor on Thailand's west coast from the visa run to Myanmar, every day around 200 people do this trip to leave the country, take a ferry to Kawthaung get a stamp and come back for another 2 week visa, the other purposes is, it's the home of Thailand biggest fishing fleet.
In general this is a rather remote tourist destinationand the least populated area, this has something to do with the weather, means rain. Right behind the coast are the blue mountains and the clouds coming in from the Indian Ocean empty their water on them and the coastal region.
Business is, the catch of the fishing vessels which come in and out every day is carried in the night to Bangkok via refrigeration trucks. The other business is gambling at the Myanmar side where a Thai has set up a casino on a island just opposite the town, don't mistake it for Rayong on the eastern side of the gulf of Thailand, south of Bangkok and Pattaya, also serves other purposes. All yachts who do liveaboard tours out of Phuket have to call at this port to handle paperwork for diving tours into the Myeik Archipelago around 300km further north.
A typical daytrip from Phuket to up here runs via Khao Lak,off this village are the Similan Islands one of the best dive sites in the world. The area around shows dark green colors everywhere with red, yellow, blue and other colors in between, it's a typical tropical countryside in lush green vegetation bordering the emerald waters of the Andaman Sea.
There is a intense shrimp and fish farming industry along the coast supplying fresh seafood together with the catch the fisherman land at the harbor every day.
Currently the main purpose from a tourist perspective is the visa run.