And as our Photo Album shows, the beauty of the appealing outcrops and their surroundings has been enhanced by a respite from the pressures of tourism.
Closed from April to November 1 each year, the Similans enjoy a chance for regrowth and revival that Phuket and other nearby islands do not have.
The pressures of year-round tourism are constant and growing, along with the commercialisation of every accessible strip of sand.
Phuket must once have looked just the way the Similans do today. Although administrators now talk of ''sustainability,'' little is being done in a practical way.
Five years ago, Phuket was more appealing because its natural attractions were still quite obvious. Phuket remains appealing, of that there is no doubt.
But what will it seem like in another five years? As each year passes, the natural attractions of Phuket are diminished.
The national government now understands that Phuket must be made safe and secure for visitors - and residents - to maximise the returns from tourism.
But for Phuket to remain an appealing option, serious effort is also needed to put ''sustainability'' into practice.
The Similans returns each year after a respite, looking fresh and wonderful.
Authorities now need to work out how to ensure that Phuket's natural appeal also remains undiminished.