Most of Thailand is beautiful with great beaches, lakes and waterfalls.
The Land of Smiles is inhabited by friendly and happy people.
Go to the beaches where the Thai people go.
Don't go to the beaches where the tourists are.
There everybody swims in very brief bikini's, tangers and golden chains.
They probably get sunburned and stung by jellyfish.
The local Thai custom is to swim in clothes
and you do well to respect that and join them.
They also find people with pale skin very attractive, so don't go out and get a tan.
Exposing too much of your skin will not only earn you a sunburn,
but is also frowned at by the locals.
Not matter how hot is is, gentlemen should wear long trousers.
For ladies, pants are also acceptable,
or you can wear a skirt or a dress that covers the knee.
Sleeveless shirts or sweaters should be avoided.