Well this stinks. I got this from the charter company "Once you leave the USVI you must again clear out of customs in
St. John and back into the BVI in Sopers Hole once again"

Its a pain to have to back-track to Cruz to clear out of St Johns customs.

Thanks to everyone's feedback. The seestjohn.com is excellent and I've noted all the snorkeling spots you guys/gals have mentioned. Many thanks again and I'll post an update if we visit (the returning to clear out of customs complicates things a bit)