As a coastal nation, of course the Private Cruise industry exist. The famous spot is at Langkawi Island. One of the Private Cruise that I found got top rating in tripadvisor is Damai Indah Private Cruises. You can read all the review here at tripadvisor.
Although many made man attraction available for the public, nature activities like cruising in a yacht around untouched Island are still anyone dream. As for that it become exclusive and not affordable. When exclusive it can be a good business. That is why so important to preserved the nature.
You can read more about the private cruise at the packages here.