ASIA

VIETNAM. Halong Bay, a 50-km-long bite out of Viet- nam's northern coast, cradles a string of some 2,000 islands, each created--legend says--by dragons that descended from the heavens and scattered gems across the water. Travelers can explore some of these remote, jagged islets on a new 15-day guided sea-kayaking trip organized by Mountain Travel-Sobek of El Cerrito, California. Participants will paddle through mazes of limestone islets dotted with coral beaches, natural arches and rock gardens; they will investigate hidden lagoons, grottoes and sea caves. On most nights the group will camp on soft beaches sheltered by imposing rock towers. The tour departs June 29.

EUROPE

GLASGOW. Born and educated in Glasgow, Charles Rennie Mackintosh is acclaimed as Scotland's foremost architect and as an influential member of the Art Nouveau movement in Europe. When the designer died in 1928, he left Glasgow a legacy of masterly buildings such as the city's School of Art, tastefully decorated tearooms, elegant furnishings, fine silverwork, splendid botanical watercolors and French landscapes. In tribute to its native son and in conjunction with the city's Festival of Visual Arts, Glasgow's McLellan Galleries is mounting the largest retrospective ever devoted to Mackintosh. In 10 galleries the exhibition displays more than 300 of the artist's greatest pieces--many never before on public view--including fully furnished room settings (notably the interior of his Ladies' Luncheon Room, formerly located on Ingram Street in central Glasgow) and large-scale architectural models. Through Sept. 30.

HILLEROD. Smitten with the formal French and Italian palace gardens he encountered on his travels as a young crown prince, Danish King Frederik IV (1671-1730) commissioned his royal architect and landscape designer to create a similar Baroque showcase at the Renaissance-style Frederiksborg Castle in this town 30 km north of Copenhagen. When the garden was completed in 1725, it was one of the finest of its kind in Northern Europe. The glorious jewel flourished for some 40 years under three reigning kings, but then virtually disappeared as a result of neglect. After a three-year restoration, the castle garden has been returned to its former grandeur--resplendent with hornbeam bosquets, groomed terraces and exquisite parterre beds fashioned from pyramid-shaped yews and box hedges--and has reopened to the public.

NORTH AMERICA

SANDUSKY. Get ready to start screaming! The Mantis, a $12 million roller coaster billed as the world's tallest (44 m), fastest (97 km/h) and steepest (42-m drop at a 52 [degree] angle) stand-up supercoaster, has just opened at the Cedar Point amusement park, 90 km west of Cleveland, Ohio. The 3-min. ride joins 11 other spine-jolting roller coasters at the park, which houses the largest collection of these thrill machines anywhere in the world.