One of the finest vessels of her size sailing the waters of the Galapagos Islands, the Reina Silvia Galapagos motor yacht permits you to discover the "enchanted islands" in relaxed comfort.   Named after H. M. Queen Silvia of Sweden, the Reina Silvia operates carefully organized cruises in the Galapagos archipelago. Built by Lydia Inc. of Stuart, Florida, USA, Reina Silvia is 90 feet long, and was redesigned to create a pleasant atmosphere for groups of 12 to 16 passengers.   With a highly trained crew of eight, including a multilingual naturalist guide, Reina Silvia accommodates her guests in six staterooms. Two of these staterooms are doubles that can be configured with either two twin beds or one king-sized bed. The four additional staterooms are furnished with two lower beds, and can be configured with twins or a king, along with one Pullman-style bed. These are considered doubles but can be used as triples upon request. Each stateroom has en-suite facilities, including a shower, a lavatory and a vanity.   The yacht is fully air-conditioned and features up-to-date security, navigational and communications equipment, including a satellite telephone system. From the well-equipped galley, excellent cuisine is served in the spacious dining room. This area and the top deck lounge are also used for lectures and conferences.   The yacht has an aft swimming/diving platform, as well as an extended bow pulpit for whale- and dolphin-watching. An onboard desalination plant provides all the freshwater needed.