What kind of a pool finish is this?

[unheard]

What kind of a finish is this?

At first I thought it's PebbleTec/PebbleCrete, but now I think it's something else.

 

[Bagwain]

A good chance it is plaster. It won't last long.

[Saanim]

There are different qualities and prices of paint that is sometimes used instead of tiles or foils.  Needed repainting after certain time, depending on the paint quality and chemistry of the pool water.  

In general, not really advantageous for Thailand where a tiling is cheap and paints are expensive. 

Besides, with the tiles the pool improves its water proof, not relying only on cladding by the concrete mortar.