THE GRENADINES consist of 32 islands and cays, some of which are reachable by plane, but most only by boat. Each island has its own distinct character and appeals to a particular crowd, whether it's the exclusive decadence of Mustique or the rustic appeal of Union , or the yachters and sunseekers who flock to Bequia or those who wish to get away from it all in tiny Mayreau . All, however, tend to share superb diving and snorkelling opportunities, as well as pristine white-sand beaches and a relaxed atmosphere.