White "line" is the wave" coming in.
Blue "outline" is the hills on the other side of the water.
I've been searching for pics or maps of that beach area. I know the pics don't give us much info., but I find it hard to believe those are hills etc. Looking at the map it's hard to believe those are hills...I know it depends on the angle etc., but darn...either way.
http://www.molon.de/galleries/Thailand/Krabi/RaiLehPhraNang/